Crab Maison

Name: Crab Maison
Ingredients: 1⁄2 cup mayonnaise; 2 tbsp. high quality olive oil; 2 tsp. white wine vinegar; 1 tsp. Creole or Dijon mustard; 1 tsp. small capers, rinsed, drained, and finely chopped; 1⁄2 tsp. finely chopped flat-leaf parsley; 1⁄2 tsp. kosher salt; 1⁄8 tsp. freshly ground white pepper; 3 green onions, finely chopped; 1 lb. jumbo lump crab meat; 12 large leaves butter lettuce; 4 slices tomato, halved