Mushroom Sauté

Soak mushrooms in bowl of water and some lemon juice for 5 minutes. Hold paring knife by back of blade, not handle. Orient the knifepoint to center of mushroom cap. Pivot blade into cap on bias. Rock mushroom toward you and knife away from you in a smooth, easy motion, beveling out a strip. Repeat with remaining mushrooms.

Preheat broiler.

Heat butter in a 12-inch heavy skillet over moderately high heat until foam subsides, then cook mushrooms, cap sides down, with 1/4 teaspoon salt and 1/8 teaspoon pepper, until golden brown, about 2 minutes. Turn mushrooms over with tongs and sprinkle with remaining 1/4 teaspoon salt and 1/8 teaspoon pepper, then cook until mushrooms are tender, about 2 minutes more.

Sprinkle with lemon juice.

While mushrooms are cooking, arrange bread triangles in a shallow baking pan. Broil 5 to 6 inches from heat, turning over once, until lightly toasted, about 2 minutes total (watch carefully).

Put 3 toasts on each of 4 plates, then divide mushrooms among them with a slotted spoon.

Drizzle pan juices over mushrooms and sprinkle with parsley.