1. Wash the collard greens in several changes of water. Remove the stems. Stack the greens a few at a time and cut crosswise into 1/2-inch wide strips. Bring a large pot of water to the boil, add the collard greens and cook 10 minutes. Drain and rinse with cold water. Squeeze out the excess moisture. 2. Heat the oil in a large skillet. Add the onion and jalapeno; saute 5 minutes. Add the tomatoes and cook 1 minute. 3. Stir in the greens, salt and pepper. Cook 5 minutes. Stir in the lemon juice and cook 1 minute. Serve.