Shrimp in Sherry Butter Sauce

Ingredients

• 0.5 teaspoon peppercorns whole black
• 1  carrots halved
• 0.5 cup medium-dry sherry 
• 1.5 tablespoons flour all-purpose
• 2 teaspoons juice of lemon fresh to taste
• 1  onion minced halved
• 2  parsley sprigs fresh
• 1.5 teaspoons salt 
• 3 pounds shrimp in shell rinsed peeled per pound), , , and shells reserved
• 1  thyme sprig fresh
• 1  turkish or 
• 0.5 cup butter unsalted softened cut into tablespoon pieces and
• 1 tablespoon vegetable oil 
• 8 cups water 

Equipment

• bowl
• paper towels
• whisk
• pot
• sieve
• baking pan
• slotted spoon

Directions

1. Heat oil in a 4- to 5-quart heavy pot over moderately high heat until hot but not smoking, then cook shrimp shells, stirring, 1 minute.
2. Add water, onion halves, carrot, bay leaf, parsley, thyme, peppercorns, and salt and simmer, uncovered, 30 minutes.
3. Pour stock through a large sieve lined with a dampened paper towel into a large bowl, discarding solids. Return stock to cleaned pot.
4. Add shrimp and cook over high heat (stock will be hot but not boiling), stirring frequently, until just cooked through, about 2 minutes.
5. Transfer shrimp with a slotted spoon to a large shallow baking pan, spreading in 1 layer to cool quickly. Boil stock until reduced to about 1 1/2 cups, 30 to 40 minutes, then transfer to a bowl.
6. Stir together flour and 1 1/2 tablespoons butter until a paste forms, then set aside. Cook minced onion in 1 tablespoon butter in cleaned pot over moderately low heat, stirring, until softened, about 3 minutes.
7. Add Sherry and boil until liquid is reduced to about 1/3 cup, about 2 minutes.
8. Add shrimp stock and bring to a simmer, then reduce heat to low and whisk in remaining 5 1/2 tablespoons butter until just incorporated.
9. Whisk in flour paste, bit by bit, and simmer sauce, whisking, until slightly thickened, about 2 minutes.
10. Add lemon juice, shrimp, and salt and pepper to taste and cook over moderate heat, stirring, until shrimp are just heated through, about 1 minute.
11. Shrimp can be cooked (in stock) and stock reduced 1 day ahead. Cool stock, then chill shrimp and stock separately, covered.