Heat a large cast-iron skillet over medium heat. Add tomatoes, jalapeños, and garlic; cook 15 minutes or until tomatoes are blackened. Turn frequently. Remove from pan; cool slightly.
Peel, seed, and chop tomatoes; place in a medium bowl. Remove and discard the stems and seeds from jalapeños, and finely chop. Add to tomatoes. Peel garlic, and finely chop. Add to the tomato mixture. Add onion, cilantro, lime juice, and salt to the tomato mixture, and toss well to combine.