Bean and Tuna Salad (Insalata di Fagioli e Tonno)

3 cups water
1/2 pound dried white kidney, Great Northern or navy beans*
1/3 cup olive or vegetable oil
3 tablespoons red wine vinegar
1 teaspoon salt
Freshly-ground pepper
1 medium Spanish, Bermuda or red onion, thinly sliced
1 (6 1/2 ounce) can tuna, drained
Snipped parsley

Heat water and beans to boiling; boil 2 minutes. Remove from heat; cover and let stand 1 hour. Add enough water to cover beans if necessary. Heat to boiling; reduce heat. Cover and simmer until tender, 1 to 1 1/2 hours (do not boil or beans will burst). Drain and cool.

Mix oil, vinegar, salt and pepper; pour over beans and onion in shallow glass or plastic dish. Cover and refrigerate, stirring occasionally, at least 1 hour. Transfer bean mixture to serving platter with slotted spoon. Break tuna into chunks; arrange on bean mixture. Sprinkle with parsley.

* 2 (15 to 20 ounce) cans cannellini or other white beans, drained, can be substituted.