Directions

1. Bring a pot of water to a boil with 1 1/2 tsp. salt. Cook pasta according to package directions until just tender (10-12 minutes). Drain pasta in a colander and rinse thoroughly with cold water. Set aside.
2. While pasta cooks, arrange bacon in a large frying pan. Cook over medium-high heat, turning once, until browned and crisp, 8-10 minutes. Transfer to paper towels and let cool; then roughly crumble bacon and set aside.
3. In a medium bowl, whisk together sour cream, mayonnaise, green onion, parsley, dill, garlic powder, pepper, remaining 1/4 tsp. salt, and the onion powder. Stream in buttermilk and whisk until dressing is smooth.
4. Add drained pasta to a large bowl along with bacon, tomatoes, and three-quarters of the dressing. Toss salad until components are thoroughly coated. Taste and add additional dressing, salt, and pepper to taste if you like.
5. Salad can be served immediately, but for best flavor, wait to add lettuce, cover bowl, and chill pasta salad 2-4 hours. Just before serving, toss lettuce with the pasta salad and additional dressing if desired.