Combine 2 tbsp minced red onion and 1.5 tbsp red wine vinegar in a small bowl and let stand for 5 minutes.
Add 2 tsp olive oil, 1/4 tsp salt, 1/4 tsp finely ground black pepper and 1/4 tsp dijon mustard to the onion and vinegar. Whisk well.
Place the 6 cups torn curly leaf lettuce, 1/4 cup thinly sliced red onion and 1 pint halved cherry tomatoes in a large bowl and drizzle with dressing. Gently toss to combine.
Keyword barbecue side dish, green salad recipe, santa maria style recipes, santa maria tri tip side dish