Heat olive oil in a skillet over medium heat; saute onion for about 5 minutes. Add salt, pepper, tomato sauce and water; bring mixture to a boil and add peas; reduce heat and simmer for about 30 minutes.
Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain.
Stir cooked pasta and cheese into tomato sauce mixture. Cover pan and turn off heat; let stand for 20 minutes.