In a sauté pan, heat the olive oil over medium heat. Add the onions and zucchini and sweat for 2-3 minutes. Add the ground meat and taco seasoning and cook until done, stirring around frequently to break up any large bits of meat. Remove from heat and set aside to cool.
In a large bowl, combine all the remaining ingredients except for the thousand island dressing. Toss together evenly. Once the meat has cooled almost to room temperature, add it and the dressing and mix until everything is coated evenly. Serve immediately.