In a bowl, stir together the avocado. salt and pepper, lime, and garlic. Mash until smooth. Cover by placing plastic wrap directly over the surface of the avocado. Set in the fridge until ready to use.
Slice a sweet potato in half the long way. Slice a 3/4 inch plank off of each half leaving the skin still on. These will be your "toast". Season with salt and pepper.
Preheat a pan to medium heat and add some olive oil. Add the two potato "toasts" to the pan, and cook about 10 minutes per side, charring the potato but not burning. Cook until the inside is tender, about 15 to 20 minutes total.
Allow the sweet potato to cool slightly, then spread each toast with a generous amount of avocado. Top with the garnishes of your choice and serve.