- For fried leeks:
- 2 large leeks (white and pale green parts only), trimmed
- 4 cups vegetable oil
- For soup:
- 1 1/2 cups shucked small oysters, drained, plus
- 1 1/2 cups oyster liquor or bottled clam juice
- 2 medium leeks (white and pale green parts only), chopped
- 2 (8 ounce) russet (baking) potatoes
- 1 teaspoon salt
- 3 tablespoons unsalted butter
- 3 1/2 cups water
- 1 cup half-and-half
- Pinch of cayenne
- Cut leeks crosswise into 2-inch lengths, then cut lengthwise into enough very thin strips to measure 2 cups. Wash leek strips in a bowl of cold water, agitating them, then lift out and pat dry.
- Heat oil in a deep 4-quart heavy saucepan until it registers 360 degrees F on thermometer. Fry leeks in 8 batches, stirring, until golden, about 10 seconds per batch. Transfer as fried with a slotted spoon to paper towels to drain. Cool completely (leeks will crisp as they cool).
- Pick over oysters, discarding any bits of shell, and rinse well. Wash chopped leeks in a bowl of cold water, agitating them, then lift out and drain well. Peel potatoes and cut into 1/2-inch cubes. Cook leeks, potatoes, and salt in butter in a 4-quart heavy saucepan, covered, over low heat, stirring occasionally, until leeks are golden and potatoes are beginning to soften, about 15 minutes. Add water and simmer, covered, over moderate heat until potatoes are very tender, about 10 minutes. Puree soup in batches in a blender until very smooth (use caution when blending hot liquids), transferring to a bowl.
- Return soup to saucepan. Add oyster liquor and half-and-half and bring to a simmer over moderate heat, stirring occasionally (do not boil). Add oysters and cayenne and cook, stirring occasionally, just until oysters become plump and edges curl, about 3 minutes. Season with salt.
- Serve soup topped with fried leeks.