Everyone knows that garlic butter goes with seafood. But this recipe for, inspired by the famous Vietnamese restaurant in San Francisco, takes it a couple steps further by making the best ever garlic butter to dress crab ever. This also works really well with a pre-cooked crab from Costco.

Thanh Long is a landmark Vietnamese seafood restaurant in San Francisco that opened in 1971. They are renowned for their garlic noodles and roasted garlic crab.
In case you can't make it to the restaurant, this recipe is at least a more affordable version of the famed dish, if you make it at home, and comes close to mimicking that addictive butter sauce.
If you love crab, you'll also want to check out this crab roll, a quick and easy crabmeat pasta, and these inspiring recipes for crabmeat.
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Ingredients
A fish butter sauce became popular in Vietnam via French colonialism. I suspect this the sauce is based on this fusion sauce that adds the ubiquitous fish sauce, sugar, and black pepper to a traditional garlic butter.

- Fish Sauce - Just a touch is used of this powerful, salty fermented anchovy liquid. You won't notice it too much, and it won't smell any fishier than the hot boiled crab.
- Fresh garlic - I've also tried it with garlic powder, but I think fresh garlic gives this sauce better, grown-up flavor.
- Butter - I think they use clarified butter (melted butter with the fat solids removed), since it is much less susceptible to burning. It also looks prettier on the plate because you don't have these wads of white foam sliding around. The fat solids make the butter taste better though. Alternately, use non-hydrogenated margarine.
See recipe card for quantities.
Vietnamese Fish Sauce Butter
When the French colonized Vietnam in the 19th century, they brought their own pantry of baguettes, butter, coffee, and wine.
Over time, those ingredients slipped into local cooking and took on a Vietnamese personality. The baguette became bánh mì, stuffed with pork pâté and pickled vegetables. Flan showed up on café menus, made with sweetened condensed milk.
Fish sauce butter is not quite as well known as the beloved banh mi sandwiches, but it is perhaps more often found in home kitchens, served with everything from grilled shrimp, steamed vegetables, or a plain baguette.
Instructions
The hardest part of this recipe is cleaning and cracking the crab. In the restaurant, they serve it to you already cracked, so some of the butter sauce has oozed into the crevices when it's roasted.

- Step 1: Make the fish sauce butter. Plenty of black pepper should be added at the end.

- Step 2: To crack the crab, remove the carapace and clean off the guts and gills. Gently separate off each leg. Crack each leg a couple times in various sections so the meat is easier to remove.

- Step 3: Lay the ccracked crab pieces onto an unlined baking sheet. Pour over the sauce.

- Step 4: Roast in a preheated 400 degree oven for 10-12 minutes piping hot.
Hint: Using clarified butter avoids the risk of burning the milk solids or browning the butter, which results in a different flavor.

How to Cook Dungeness Crab
Boil the crab in water if you don't already have a cooked one. The rule of thumb for cooking is 7 minutes per pound after the water has come to a boil with the crab. Make sure the pot is covered.
I start with a pot large enough to fit the crabs. I put in a couple inches of water and lay the live crabs in, belly side up, to allow the guts to sink more towards to bottom of the shell rather than on top of the crabmeat. Since these area more steamed than boiled (due to less water in the pot), I boil for at least 10 minutes per pound of crab in a covered pot.
To be humane, you can kill the crab first just before cooking by sticking a paring knife through the apron (underbelly) of the crab. This does cause more of the guts to leach out when cooking.
I don't salt the water, because I think the crabmeat is already salty enough, and it's going to be swathed in butter sauce.
If you overcook the crab, the legs will fall off, but you know that it's cooked long enough. You're going to pull the legs off anyway in this recipe, but overcooking will result is dryer meat if all the juice has leached out of it.
Alternately, if you undercook the crab, the crabmeat will stick to the shell, and it's a bit harder to pull out.
So just stay near the pot of boiling crabs and try not to over or undercook it. You can test a piece of crab by seeing how easily a leg comes off. If it doesn't come off easily, it needs more time. If it comes off very easily, it's ready. If it's already fallen off, it's overcooked. You also want to watch the pot, since it has tendency to bubble and boil over.
Even though, the cooked crab is again cooked in the oven in this recipe, it's more reheating the crab with the butter sauce, rather than cooking the crab further.
Storage
Since the crab has already been cooked, and you're reheating the crab for the second time, this should be consumed the same day.
If you have leftover, pull the meat out of the shell and use the crabmeat within a couple days with any leftover crab butter.

Top Tip
Dungeness crab costs a lot and not always available, depending on the time of year. In CA, the season runs from December to April but varies depending on the part of CA.
In case you don't have access to fresh Dungeness crab, this sauce will work really on other types of seafood such as:
- Shrimp, especially head on whole shrimp with the shells
- A meaty white flesh fish, such as halibut, ling cod, or rock fish
- Clams, mussels, and oysters
Since these are not as large as the crab, they don't need to be pre-cookied. You can put the raw seafood on the baking sheet, layer on the fish sauce butter, and roast until cooked through (or reaches an internal temp of 145 degrees F).
Recipe
Roasted Garlic Dungeness Crab (Thanh Long Copycat)
Ingredients
- 1 ea cooked Dungeness crab (about 1-3 lbs), see Note 1
- 8 Tb butter or non-hydrogenated margarine like Earth Balance
- 1 teaspoon garlic minced
- 1 teaspoon sugar
- ½ teaspoon fish sauce or salt if you don't have fish sauce
- ½ teaspoon black pepper
Instructions
- Oven prep. Preheat the oven to 400 degrees F. Have a rack set in the middle part of the oven.
- Prep the crab. The crab legs should be separated from the body and cracked in a couple spots with a crab cracker or mallet. The crab body should be cleaned of guts and gills. Spread the crab legs and body onto a baking sheet. Save the carapace for garnish.
- Make fish sauce butter. Melt the butter, garlic, and sugar together over medium heat in a small saucepan or skillet. Swirl gently to distribute the garlic and sugar. Once the garlic sizzles and sugar is dissolved, turn off the heat. Let the garlic and milk solids sink to the bottom. (About 5 minutes).
- Optional: At this point, you can gently pour off the liquid butter to another container, while leaving the milk solids and minced garlic behind. This essentially makes clarified butter that is less subject to burn in the oven and is more of the restaurant-y technique. (I do this step depending on my mood - do I feel rustic or restaurant-y?)
- Pour sauce over crab. Mix in the fish sauce and black pepper to the butter sauce. Drizzle over the crab parts on the baking sheet. Usually, some juice from the crab will be drawn out during cooking and add to the volume of the butter sauce.
- Cook. Pop the baking sheet into the oven. Roast for 10-15 minutes, until the crab is heated through.
- Plate. Remove from the oven. Use tongs or quick hands to arrange the legs and body into the shape of a live crab. Drizzle over the remaining butter sauce from the baking sheet. Put the carapace on top for garnish.
- Serve with lemon wedges, crab crackers, bibs to wear if needed.
Notes
- To boil your own fresh Dungeness crab,
- This may seem like a lot of butter, and it is. but you don't end up using it all, but it helps if there is a little extra, so you can easily dip each piece of crabmeat.
- 1 crab can be shared between 2 people.
Nutrition
Fortune Cookie
When you are content to be simply yourself and don’t compare or compete, everyone will respect you.
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