Oatmeal is the heartiest I find.
Get plain oatmeal, one cup of milk/soy milk, slice up either one banana, apple, or a handful of strawberries or blueberries, depending on what you prefer. And instead of sugar, use two table spoons of orange blossom honey. Toasted walnuts if you want and voila.
Another thing is two slices of bread, toasted brown with some butter. Half of an avocado sliced, two slices of sharp white cheddar cheese, fresh sprouts with little salt and pepper to taste for a hearty sandwich.
Another this is an omelet using flour if you don't do eggs. You make it sort of like the pancake batter except not sweet, add in all your favorite veggies>> tomatoes, green peppers, onions, mushrooms etc etc. What ever you like and cook that and have it with some non-fat plain yogurt.
Another thing is lemon coconut peanut rice which is very good, hearty, and perfect for morning because it's light for the most part.
You can do grits.
Oatmeal is hard to find in my country, it is also very very very expensive!! I mean a small package would cost around 20 dollars or something! I have heard a lot of great things about it! The same thing for soy milk!
I guess I can manage to cook the rest!