• Step 2

Heat 1 tablespoon oil in a 12-inch heavy nonstick skillet over moderately high heat until hot but not smoking, then sauté asparagus, stirring occasionally, until just tender, 5 to 6 minutes. Transfer with a slotted spoon to a plate, reserving skillet off heat (do not clean).

• Step 3

Pat scallops dry and sprinkle with fresh ground pepper and 1/2 teaspoon salt. Add 1 tablespoon oil to skillet and heat over moderately high heat until hot but not smoking, then sauté half of scallops, turning over once, until browned and just cooked through, 4 to 6 minutes total. Transfer scallops with tongs to another plate as cooked.

• Step 4

Wipe out skillet with paper towels, then add remaining tablespoon oil and heat until hot but not smoking. Sauté remaining scallops, turning over once, until browned and cooked through, 4 to 6 minutes total, transferring to plate. (Do not wipe out skillet after second batch.)

• Step 5

Carefully add wine and vinegar to skillet (mixture may spatter) and boil, scraping up brown bits, until liquid is reduced to about 2 tablespoons, about 1 minute. Add any scallop juices accumulated on plate and bring to a simmer.

• Step 6

Reduce heat to low and whisk in butter, 1 tablespoon at a time, until incorporated.

• Step 7

Add asparagus and remaining 1/4 teaspoon salt and cook until heated through, about 1 minute. Add roasted Thai chili (if desired). Strain pasta and toss with a sprinkling of olive oil.

• Step 8

Add 1/2 cup of reserved pasta water and allow to reduce for 1 minute.

• Step 9