Heat a stove-top or charcoal grill. To make the sauce, place the tomatoes, celery, onion, fennel, horseradish, hotpepper sauce, 1 tablespoon olive oil, and 1 clove garlic ina food processor, and process for 2 minutes. Pass through a fine sieve, and season to taste with salt and pepper. Chill. In a large skillet over medium high heat, warm 2 tablespoons olive oil and 2 crushed garlic cloves. Add arugula and toss for one minute, until wilted. Cut langoustine tails lengthwise, brush with olive oil and grill for 2 minutes. To serve, place arugula and parsley at center of 4 plates, set grilled langoustines on top and drizzle sauce around.
Recipe courtesy of Marc Murphy, Executive Chef La Fourchette, NYC