In saucepan, place shrimp in enough water to cover them. Add salt, peppercorns and bay leaf. Simmer about 3 minutes until shrimp turn pink. Remove shrimp, let cool, then shell and devein. (Shrimp will be more tender and flavorful if cooked in their shells).
In a skillet, toast seeds until they start to pop. Add clam juice, cilantro, chiles, onion and seeds to blender.
Puree until smooth. Melt butter in skillet and add sauce. Cook over low heat 10 minutes Stir in shrimp. Remove from heat and add sour cream. Return to heat until just heated through. Thin with dry white wine if necessary.