Cook the pasta in boiling salted water for about 10 minutes. In the meantime clean and wash the peppers and cut them into narrow strips. Peel onions and cut into slices. Bring red wine vinegar and 100 ml water to the boil and cook the onions for about 5 minutes.
Drain mussels and celery separately. Clean, wash and drain the rocket. Take out onions and put aside. Drain the pasta and let it drain. Peel garlic and press it through the garlic press.
Mix balsamic vinegar and garlic, season with salt and pepper. Fold in the oil bit by bit. Mix noodles, mussels, onions, celery and pepper strips. Pour the vinaigrette over the pasta and let it steep for about 30 minutes.
Mix the pasta and mussel salad with the rocket salad and arrange in a bowl.