Heat oven to 425°F and spray a 9x13-inch casserole dish with nonstick spray. Line a large, rimmed baking sheet with foil and set the casserole dish in the middle of the baking sheet.
In a medium bowl, combine refried beans, 1 can drained Ro-tel tomatoes, hot sauce, and ¼ cup cilantro; set aside.
Place beef in a large skillet set oven medium heat. Cook until brown throughout, about 6-8 minutes, breaking apart the meat while it cooks. Drain into a colander; set aside.
Add 1-tablespoon oil and onions to the skillet and set over medium heat. Cook the onions about 5 minutes, stirring often, or until translucent and tender.
Add garlic, chili powder, cumin, coriander, and oregano and cook, while stirring, an additional 1-minute.
Add browned beef, 1 can (drained) Ro-tel tomatoes, corn, vinegar, brown sugar, and juice of 1 lime. Season to taste with kosher salt and black pepper; stir well.
Stir and cook about 5-10 minutes or until juices reduce and mixture thickens.
Spread the bean/tomato mixture evenly into the prepared baking dish, and sprinkle 2 cups cheese over the top.
Spread the beef mixture evenly over the bean mixture and top with the remaining cheese.
Cover the cheese layer with a single layer of tater tots and press down gently.
Place the casserole dish (set inside the rimmed baking sheet) on the middle rack of the oven and bake at 425°F for 30-40 minutes or until bubbly and the tater tots are dark golden brown.
Transfer dish to a cooling rack and cool 5-10 minutes before serving.
Garnish with your favorite toppings.
Enjoy!