What about pickling, making chutney or relish or dehydrating the onions?
Dehydrate onions with tomatoes, garlic and fresh herbs, course grind and put in jars. Can be added to soup, stew, sauce and casserole. Or reconstitute with bit of hot water, olive oil and sweet balsamic vinegar, spread on ciabatta, pizza base, tortilla wrap, add cheese of choice and other goodies, peppers, mushrooms, chicken or beef mince, etc. to make snack or meal.