Cook pancetta in a large skillet over medium-low heat, until crispy. Remove with a slotted spoon, and drain on a paper towel-lined plate. Set aside. Pour excess grease out of the skillet, reserving 3 tablespoons of the pancetta drippings.
Season the scallops with salt and white pepper. Saute the scallops in the reserved pancetta drippings for 2 to 3 minutes or until the scallops have a nice sear on each side. Add garlic to the pan and cook an additional 30 seconds. Remove the scallops and garlic from the pan, and place in a large, heat-resistant bowl. Toss tomato halves with the warm scallops. Add the reserved pancetta.
In a small bowl combine the extra-virgin olive oil, white wine vinegar, lemon juice, and the shallots. Whisk until well blended. †Pour dressing over warm scallop mixture, tossing to coat. Adjust seasonings with salt and freshly ground black pepper. Sprinkle chopped marjoram and parsley over the salad, and toss to coat.
Arrange two lettuce leaves on each salad plate. Divide the scallop salad among the 4 plates, on top of the lettuce. Serve immediately.
Yield: 4 servings