Rinse rice in cold water. Then place both kinds in a saucepan with cold water and salt. Cover and bring to a boil. Reduce heat and simmer gently, covered, until tender, from 35 to 45 minutes.
Meanwhile, stir pecans in a small ungreased frying pan set over medium heat. When fragrant and hot, remove pecans from pan and set aside. Add butter, red pepper and onions to pan and sauté about 3 minutes. When rice is tender, drain off excess water. Then stir in pecans, red pepper and onions. Add salt and pepper to taste and serve.