1. In a small bowl, stir together the diced tomatoes, red onion, cilantro, jalapeño, lime juice, salt, and black pepper. Set aside.

2. Heat a large skillet over medium-high heat and add the ground beef and chopped onion.

3. Cook the beef until browned, breaking and chopping it into small pieces as it cooks.

4. Stir in the garlic and cook for 30 seconds.

5. Add the taco seasoning, tomato paste, and water, then stir until the meat is evenly coated and juicy.

6. Reduce the heat to low and mix in the Monterey Jack and cheddar until melted.

7. Split the hoagie rolls and spread the insides with butter.

8. Toast the rolls in a skillet or under the broiler until lightly golden.

9. Spoon the cheesy beef mixture into each roll.

10. Top with the fresh tomato mixture and serve immediately.