Cod with Coconut, Lime, and Lemongrass Curry Sauce

Modified from this epicurious recipe.

Sauce
2 shallots, peeled and cut into large chunks
3 garlic cloves, peeled
1 lemongrass stalk, sliced into rounds
1-inch knob ginger, peeled and cut into chunks
1 tablespoon butter
3 kaffir lime leaves
1 tablespoon red or green curry paste
3 cups chicken stock
3/4 cup fresh coconut milk, or canned
4 cilantro sprigs
Fine sea salt to taste
Freshly ground pepper to taste
1 tablespoon fresh lime juice

4 7-ounce cod fillets, 1 1/2-inches thick
salt and freshly ground pepper

Place the shallots, garlic, lemongrass and ginger in a small chopper, and chop until minced together. Heat the butter in a skillet, and add the chopped ingredients. Put in the lime leaves and curry paste, and saute until the chopped ingredients are tender and colorless, about 5 minutes. Add the chicken stock, bring to a boil, and adjust the heat to simmer, uncovered, for 15 minutes. Add the coconut milk and cilantro, simmering for 5 more minutes. Remove from heat, season to taste with salt and pepper, and remove the lime leaves. Return to a chopper or blender and puree, then set aside.

Heat several tablespoons of oil in a skillet, and rinse the fish and salt and pepper on both sides. Saute the fish on the first side until golden brown and crusted, then flip and finish the fish on the other side until cooked properly. Serve over rice, with sauce poured on top; they also suggest bok choy sauteed in butter on the side. Enough for 4.