Cook Once, Eat Twice Healthy Vegetable Ratatouille: Cook Once, Eat Twice Colombe Jacobsen-Derstine | June 19, 2012 My ratatouille is in the oven, and I???m enjoying the aromas of summer???a winning combination of red peppers, eggplant, zucchini, tomatoes, and onions, with hints of fresh herbs such as rosemary and basil.