In a large skillet, heat oil over medium heat. Add onions and saute for 5 minutes, until tender. Add garlic and jalapeno and sauté until cooked, 3 minutes. Turn heat up to medium high and stir in mustard greens. Add water, cover, and cook for 3 to 4 minutes. Stir in spinach, yellow and red pepper, Creole spice, salt and tomato. Cover and cook for 3-4 minutes, stirring until greens are cooked evenly.
COOKING TIP: For less heat from the jalapeno, remove the seeds and ribs before chopping. For maximum heat, leave the seeds and ribs on.