1. Preheat the oven to 375°F.
2. In a large pan, over medium-high heat, add the oil. When the oil begins to swirl add the beef, Worcestershire sauce, paprika, a pinch of salt and a few grinds of pepper. Cook, breaking up the meat with a spoon or spatula, until meat is browned, about 6-8 minutes.
3. Stir in tomato paste and sauté for a few minutes to intensify the flavor. Add stock and bring to a simmer. Season to taste. Remove mixture to a bowl with a slotted spoon leaving the fat in the pan.
4. In the same pan, add the peppers and onions, zucchini, carrots, a pinch of salt and a few grinds of pepper. Cook while tossing until tender, but still a bit crunchy about 6-8 minutes. Remove from heat.
5. In the bottom of a 9- by 13-inch casserole dish, layer in this order: half of the beef (pressing it down to level it), then sprinkle half the cheese over the beef evenly. Pour the remaining half of the beef over the cheese (and press down to level again). Add the vegetables then the remaining cheese and press to level. Top with the tater tots in a neat row like little soldiers. Sprinkle the top with paprika and bake for 25 minutes or until edges on the tots turn golden brown