Put the veggies into the pot in the order that it will take them to cook. Onions take the longest, so they go in first. If you are using broccoli or cauliflower, they will need to go in next. Tomatoes and spinach take the least amount of time and should be added at the end.
Be sure to allow the balsamic dressing to cook down a little with the veggies. This will help to mellow out the flavor of the balsamic vinegar.
