Whisk sour cream dressing:
Make the dressing by whisking sour cream, red salsa, ground cumin, salt, and lime juice in a bowl until smooth.Grill or steam corn:
Grill or steam the corn until heated through.Chop vegetables:
Chop the romaine lettuce, dice the bell pepper and tomatoes, and slice the green onions.Toss salad ingredients:
In a large bowl, gently toss the prepared vegetables with black beans, cooked corn, crushed tortilla chips, and grated cheese.Drizzle dressing over salad:
Right before serving, drizzle some dressing over the salad and toss lightly. Serve remaining dressing on the side.