In a pan , over low heat, heat up the olive oil with a clove of onion. Then add smoked salmon and cook for 10 minutes.
In another pan heat up the olive oil with the rest of onion with peas. Finally mix them in the same pan.
In meantime cook Spaghetti in plenty of salted boiling water, drain the pasta and let it cook in the pan with the sauce.
Add butter and pepper. Serve in warm plates.