Preparation Heat 2 tablespoons oil in heavy large pot over medium-high heat. Add onion and sauté until tender, about 4 minutes. Add mussels, 2 tablespoons parsley, anchovies, and garlic, then liqueur; stir to blend. Boil 1 minute. Add tomato sauce and wine. Cover and cook until mussels open, about 6 minutes (discard any mussels that do not open). Season sauce to taste with salt and pepper. Divide mussels and sauce among 4 shallow bowls. Drizzle mussels with remaining 2 tablespoons oil and sprinkle with remaining 2 tablespoons parsley.
Preparation Heat 2 tablespoons oil in heavy large pot over medium-high heat. Add onion and sauté until tender, about 4 minutes. Add mussels, 2 tablespoons parsley, anchovies, and garlic, then liqueur; stir to blend. Boil 1 minute. Add tomato sauce and wine. Cover and cook until mussels open, about 6 minutes (discard any mussels that do not open). Season sauce to taste with salt and pepper. Divide mussels and sauce among 4 shallow bowls. Drizzle mussels with remaining 2 tablespoons oil and sprinkle with remaining 2 tablespoons parsley.