In a small bowl whisk the dressing ingredients.

Arrange the tomato slices on a serving platter. In a small bowl mix the olives, celery, and onion.

In a large bowl combine the shrimp and scallops, add ¼ cup of the dressing, and mix well. Cover and refrigerate for 20 to 30 minutes.

Prepare the grill for direct cooking over high heat 450° to 550°F and preheat a perforated grill pan.

Prepare the grill for cooking over high heat 500°F and preheat a perforated grill pan.

Drain the seafood in a fine-mesh strainer. Spread the seafood in a single layer on the grill pan, and then cook over direct high heat, with the lid closed, until slightly firm on the surface and completely opaque in the center, 3 to 5 minutes, turning once or twice for even cooking. Wearing insulated barbecue mitts or gloves, transfer the pan from the grill and rest it on a sheet pan. Transfer the seafood to a large bowl to stop the cooking.

Drain the seafood in a fine-mesh strainer. Spread the seafood in a single layer on the grill pan, and then cook over high heat, with the lid closed, until slightly firm on the surface and completely opaque in the center, 3 to 5 minutes, turning once or twice for even cooking. Wearing insulated barbecue mitts or gloves, transfer the pan from the grill and rest it on a sheet pan. Transfer the seafood to a large bowl to stop the cooking.

Spoon the seafood over the tomatoes. Scatter the olives, celery, and onion over the seafood. Spoon some of dressing over the entire salad (you may not need all of the dressing). Top with the parsley and serve at room temperature.