In a large heavy pot, heat the oil until shimmering. Add the onions, celery and garlic. Cook until the onions start to go clear.
Add the beef, zucchini, pepper, and mushrooms. Cook, stirring until the vegetables are tender and the meat is no longer pink.
Season with the salt, red pepper, and black pepper. Serve immediately.
Promptly store leftovers in an airtight container in the refrigerator, for up to 4 days.To freeze: cool mixture completely and place in covered dish. Chill before freezing.Nutritional values are approximate and based on ⅙ the recipe.