Place onion in 2 cups water. Boil 10-20 minutes. Remove onion from water. Add raisins to butter and heat. Add rice to hot butter and raisins. Stir mixture constantly until rice is browned. Add peas (if frozen, thaw first). Add the water minus onion. Bring to boil. Simmer 5 minutes in covered pan. If any liquid remains, simmer uncovered until liquid is gone.