Prepare a large ice bath; set aside. Fill a stockpot with water; bring to a boil, and add a generous amount of salt. Add green beans and wax beans to boiling water, and cook just until they are crisp-tender and their color brightens, 3 to 4 minutes. Transfer beans to ice bath to stop cooking and to preserve the color. Drain, and pat dry with paper towels. Slice larger beans in half lengthwise. Set aside in a large bowl.
Make vinaigrette: In a small bowl, combine shallots, capers (if using), vinegar, and a pinch of salt; let stand 15 minutes. Whisking constantly, slowly add olive oil.
Meanwhile, slice peppers as thinly as possible using a sharp knife or mandoline. Add to bowl with beans. Drizzle vinaigrette over, and toss to combine; season with salt and black pepper. Just before serving, tear basil and mint leaves into small pieces, and crumble ricotta salata. Stir herbs and cheese into salad, and serve.