In a small nonreactive saucepan, combine the garlic, shallot, jalapeño and citrus zests. (To make the sauce with pan juices, discard the fat from the sauté skillet and make the sauce in the pan.) Cook over moderate heat fro about 1 minute, whisking quickly to release the flavors; don't stand over the pan or the chile fumes may make you cough. Stir in 1/2 cup of water and reduce the heat to moderately low. Add the lemon juice and fish sauce and simmer gently for 1 minute. Whisk in the peanut butter and coconut milk and simmer until thickened and flavorful, about 2 minutes. Add the cilantro. taste and add more fish sauce if needed.