1/2 c. red wine vinegar
1 tsp. mustard seed
1 tsp. cumin seed
2 lg. (about 1 lb. total) red onions, thinly sliced
1 tsp. sugar
2 lb. edible-pod peas, ends and strings removed
Salt

In a 5 to 6-quart pan, bring about 1 quart water to a boil on high heat. Add 5 tablespoons vinegar, mustard seed, cumin seed, and onions. Cook just until onions are limp, about 2 minutes. Drain in a fine strainer. Add onion-seed mixture to remaining vinegar and sugar. (If cooking ahead, cover and chill, stirring occasionally, up to a day.)

Rinse pan well and fill with about 2 1/2 quarts water. Cover and bring to a boil on high heat. Add peas and cook, uncovered, just until brighter green, 2 to 3 minutes. Drain.

Arrange peas in a shallow 3 to 4-quart casserole. (If cooking ahead, immerse peas in ice water until cold, then drain. Arrange in a casserole, cover, and hold at room temperature up to 6 hours or chill up to a day.)

Serve from cold to room temperature. Just before serving, spoon onions onto peas; add salt to taste. Makes 8 to 10 servings.