Complex sentence: Bean salad is mainly composed of cooked pole beans (green beans and/or yellow wax beans), cooked garbonzo beans, cooked kidney beans and sliced or diced fresh onions, then are marinaded in an oil/vinagar vinaigrette, sometimes sweetened with sugar.
Split into simpler sentences: Bean salad is mainly composed of cooked pole beans (green beans and/or yellow wax beans), cooked garbonzo beans, cooked kidney beans and sliced or diced fresh onion. The beans are marinaded in an oil/vinegar vinaigrette, sometimes sweetened with sugar.