In a large skillet over high heat, brown the ground beef, onions and garlic. Drain fat (not down the sink!). Stir in condensed cream of mushroom soup, milk, and green beans (or corn). Pour the mixture into a medium-sized casserole dish and layer with the tater tots.
Bake in preheated oven for about 30 minutes, or until tater tots are browned and crispy.