First, make the sloppy joe mixture: Add ground beef, onions and peppers to a large skillet and cook over medium heat until beef is browned. Add remaining ingredients to the skillet and stir to combine. Cover and cook on low for about 15-20 minutes, stirring occasionally.
While the sloppy joe mixture is cooking, preheat oven to 350 degrees.
Very lightly oil baking dish. Layer half of the tater tots on the bottom of the casserole dish. Evenly pour sloppy joe mixture on top of the tater tots. Sprinkle half the cheese on top of the sloppy joe mixture. Top with remaining tater tots and then sprinkle top with remaining cheese.
Bake casserole for 40 minutes until top is golden and lightly bubbly along the edges. Remove from oven and let cool slightly before slicing and serving. Top with sour cream and chopped green onions(optional)!