Heat a large skillet over medium heat. Break the ground beef up, add it to the hot skillet, and cook, stirring as needed to cook evenly and break up clumps, until the meat is well browned, about 10 minutes. Transfer the cooked beef to a wire-mesh.
Return the skillet to low heat while the beef drains. Add the onions and garlic and cook, stirring frequently, until the onions are a light golden color, about 5 minutes.
Add the chili powder, cumin, paprika, onion powder, and pepper. Stir to combine evenly.
Add the tomato paste and cook, stirring frequently, until the tomato paste turns a deep red, about 2 minutes.
Add the carrots, zucchini, green pepper, corn, drained beef, and water. Stir well and bring to a simmer. Continue to simmer until the taco filling mixture has a good flavor and consistency, about 20 minutes.
Toss together the lettuce and tomatoes and keep chilled until ready to serve.
To serve, use a No. 16 scoop (1/4 cup) to fill tacos with the filling mixture. Add a No. 10 scoop (3/8 cup) of the lettuce/tomato mixture. Top each taco with 2 tablespoons of the shredded cheese. Serve 2 tacos per portion.