Combine diced tomato, chopped onion, chopped jalapeño and cilantro in a bowl. Add lime juice and salt and toss to combine.
1 Medium Roma Tomato, cored, seeded and cut into ¼" pieces, ¼ Medium Red Onion, finely chopped, ½ Medium Jalapeno, finely chopped, ½ Cup Cilantro, finely chopped, 1 tablespoon Lime Juice, Pinch Salt