Vietnamese Stir-Fried Crab - cooking recipe

Ingredients

12 -14 blue crabs, live (substituting 2 live Dungeness crabs, about 3 pounds each OK)
1 cup peanut oil, for frying
2 cups flour (seasoned with salt and freshly ground black pepper)
6 tablespoons butter
6 tablespoons olive oil
3 stalks lemongrass, fresh (grassy tops discarded and bulbs finely chopped)
4 tablespoons garlic, minced
2 tablespoons hot pepper flakes
3 inches gingerroot, fresh, peeled and julienne
2 tablespoons tomato paste
3 tablespoons kosher salt
3 tablespoons sugar
1 bunch green onion, finely chopped
4 -5 serrano chilies, sliced into thin rounds (optional)

Preparation

Steam crabs then remove the top shells. Pull out spongy gill and opaque matter in center. Flip over & remove the key. Cut each crab into 2 pieces with a mallet or edge of a knife and make a crack (not all the way through) in each crab piece.
In large skillet or wok, pour in peanut oil, 1 inch deep. Heat the oil and fry the top shells of the crabs, turning until bright red & crisp. Drain on paper towel and set aside.
Dredge crab pieces in seasoned flour. Add pieces to the hot oil and fry over fairly high heat, turning frequently for 5 minutes to 6 minutes. Remove to paper towels to drain. Discard cooking oil.
Place the skillet or wok on medium heat and add butter and olive oil. When butter is melted, add lemon grass, garlic, pepper flakes, ginger and saute for 1 minute. Add tomato paste, mix well and cook for 1 minute. Add salt and sugar and simmer for 2 minutes. Add the crab pieces (not the top shells) and stir, coating the crab pieces with the sauce. Cook, stirring often, for 4 minutes to 5 minutes. Add the green onions and serrano chiles, if using, and remove from heat.
For a beautiful presentation, arrange crab pieces back in the shape of the crab. Divide 3/4 of the pan juices over the crabs. Then place the top shells back on top of the arranged pieces, pouring remaining juices on top of the shells. Serve at once.