1. Rinse soybeans with running cold water and discard any stones or shriveled beans. In 5-quart Dutch oven over high heat, heat beans and 6 cups water to boiling; cook 3 minutes. Remove from heat; cover and let stand 1 hour. Drain and rinse beans; return beans to Dutch oven.
2. Meanwhile, in 10-inch skillet over medium heat, in hot salad oil, cook onion, green pepper, parsley, and garlic, stirring occasionally, until vegetables are lightly browned, about 5 minutes.
3. Into beans in Dutch oven, stir onion mixture, salt, and 2 1/2 cups water; over high heat, heat to boiling. Reduce heat to low; cover and simmer, stirring occasionally, 1 1/2 hours or until beans are tender. Add tomato sauce and brown sugar; over medium heat, cook, uncovered, 15 minutes longer, until soybean mixture is of desired consistency, stirring frequently.