Rinse 1 cucumber (about 1/2 lb.) and 2 Roma tomatoes (about 6 oz. total). Peel cucumber and cut into 1/4-inch chunks. Core tomatoes and cut into 1/4-inch chunks. In a small bowl, mix cucumber and tomatoes with 2 tablespoons minced fresh jalapeño chilies, 1/4 cup finely chopped red onion, and 2 tablespoons lime juice.