A simple mixture of olive oil and red wine vinegar is all you need to top this flavorful salad from chef Lidia Bastianich. Also Try:Steamed Swordfish Bagnara-Style, Zucchini with Anchovies and Capers
Preheat oven to 375 degrees.
Trim onions and slice into 3/4-inch-thick rounds; brush with olive oil and season with salt. Lay onions in an even layer on baking sheet and transfer to oven. Roast until softened and caramelized, about 20 minutes. Let cool and separate into individual rings; set aside.
Place bell peppers directly over the flame of a gas-stove burner on high heat or on a grill. Roast peppers, turning with tongs, until blackened all over. (Alternatively, broil peppers on a baking sheet, turning, until skin has charred.) Transfer peppers to a large bowl, and cover immediately with plastic wrap. Set aside to steam, about 15 minutes. Peel peppers; discard skins. Remove stems, seeds, and ribs, and cut each pepper lengthwise into 8 strips.
Place potatoes in a large pot and fill with just enough water to cover. Bring to a boil over medium-high heat and cook until potatoes are easily pierced with the tip of a sharp knife, 15 to 20 minutes. Drain and cut into 1 1/2-inch-thick wedges; set aside.
Bring a large pot of water to a boil over high heat. Prepare an ice-water bath; set aside. Add green beans to boiling water and cook until crisp-tender, about 4 minutes. Drain and immediately transfer to ice-water bath. Let cool, drain, pat dry, and cut crosswise into 2-inch-long pieces; set aside.
Place onions, potatoes, green beans, olives, capers, and tomatoes in a large bowl; season with salt and pepper and drizzle with 1/2 cup olive oil and red wine vinegar. Toss to coat. Add lettuce leaves, tearing larger leaves in half, and toss to combine. Serve immediately.