My fave is thinly sliced cukes, plum tomatoes, green onions, mushrooms and green peppers. I make a marinade of tarragon vinegar, olive oil, fresh pepper and a dash of sugar. I mix the dressing, pour over veggies and toss it in fridge. Its like 1 tbl of herb vinegar, 1 tbl of oil, and 1/4 tsp of sugar for a quart? of veggies. After it marinates and I toss, I taste. If it's really good with spicy onions, I leave it alone. Otherwise, I might add fresh cracked pepper. Sometimes I add celery.
I'm sparse on dressings, because I think they ruin a salad. YMMV.