Prepare Filling: In a large skillet, heat oil over medium heat. Add onion and jalapeños, sauté until translucent, about 5 minutes. Stir in garlic and cook for 1 minute. Add tomato paste and stir until deepened in color, around 3 minutes. Add ground beef, taco seasoning, and salt, breaking up meat, until browned, about 8-10 minutes.

Assemble Taquitos: In a bowl, combine cheddar and pepper jack cheeses. Mix flour with lime juice to create a paste. Heat tortillas in a skillet for 30 seconds per side. Spread filling and cheese on each tortilla, roll tightly, and secure with flour paste.

Make Crema: In a bowl, whisk sour cream, lime juice, and cilantro. Season with salt to taste and let chill.

Cooking Options: For baking, preheat oven to 400°F and arrange taquitos on a lined baking sheet. Brush with oil and bake for 15-20 minutes until golden. For frying, heat oil to 375°F and fry taquitos in batches for 5 minutes until golden-brown.

Serve: Serve hot, garnished with cilantro if desired, and with zesty crema, guacamole, and pico de gallo.