I first made these when trying to follow a dairy-free, gluten-free diet. The shells are corn (no wheat) and the avocado is meant to replace the cheese on traditional tostadas, but I still love these even now that I'm back to a "normal" diet because they taste so good. The flavor comes mostly from the base foods, so some people might find this bland and you may need to find a way to spice it up a bit, perhaps some hot taco sauce or some jalapeno slices. Also, I always cook for one, so that's what the recipe calls for (easily multiplied, however). These are great for lunch with a side of fresh, ripe fruit. P.S. Measurements are approximate, I'm an "eyeballer."