Chop the vegetables: Chop the romaine. Thinly slice the red onion (follow the instructions at 1:30 of this video). Slice tomatoes in half. Thinly slice the radishes. Defrost the corn. Prepare any other add-on veggies as appropriate. Add a sprinkle of salt on the tomatoes, radishes, and corn to lightly season them.
Serve: Place the greens on the plate and top with the vegetables (and tortilla strips, if using). Top with the dressing and serve. If making in advance, refrigerate the components separately; bring the dressing to room temperature before serving.