How to Make It
Heat grill to medium-high. In a bowl, combine the brown sugar, chili pepper, cumin, 2 tablespoons of the oil, and 1 ½ teaspoons salt. Rub the mixture over the pork.
Divide the tomatoes, garlic, and jalapeños between 2 large pieces of heavy-duty foil. Drizzle with the remaining oil and season with 1 teaspoon salt and ½ teaspoon pepper. Fold and seal to form 2 pouches. Set aside.
Divide the tortillas between 2 pieces of heavy-duty foil and wrap. Set aside.
Grill the pork, turning occasionally, until an instant-read thermometer registers 145º F, 18 to 22 minutes. Transfer to a cutting board and let rest for at least 5 minutes before slicing.
Meanwhile, grill the tomato pouches, shaking occasionally, for 10 minutes. Transfer the contents to a bowl.
Grill the foil-wrapped tortillas until heated through, turning once, 3 to 5 minutes. Serve with the pork and tomato salsa.