Cook pasta in a large pot of boiling water until al dente, 8 to 10 minutes. Drain and set aside.
Heat olive oil in a skillet over medium heat. Add onion, garlic, and mushrooms and cook until onion is transparent and mushrooms are tender. Stir in smoked salmon, pesto sauce, tomato paste, fresh basil, and water; cook gently until desired consistency is achieved, 5 to 10 minutes.
Serve salmon pesto sauce over noodles.
