Maque Choux (Louisiana French)

2 tablespoons vegetable oil
1 sliced onion
1 green bell pepper, chopped
3 large fresh tomatoes, chopped
6 cups fresh corn
1 teaspoon salt
1 teaspoon sugar
1/2 teaspoon pepper

Heat shortening in saucepan. Add onion. Cook slowly until transparent. Add remaining ingredients. Cook covered over moderate flame, stirring frequently. Simmer for 45 minutes to 1 hour.