Quick pickle your radishes: Thinly slice a radish on a mandolin. Or cut thin half-moon slices with a sharp chef’s knife. Pack the sliced radish loosely into a jar. Mix together the white vinegar (apple cider vinegar works well, too), sugar, ½ cup of water and ½ teaspoon of sea salt. Bring to a boil and pour over the radishes. Let the jar cool; then, store in the fridge. Pickled radishes will keep for about two weeks in the fridge.
Heat a drizzle of oil in a large sauté pan. Add mushrooms and sprinkle with salt. Cook until the mushrooms start to release their moisture and begin to shrink, 2 to 3 minutes. Increase the heat to medium-high and continue to cook until liquid evaporates and mushrooms begin to brown, about 5 minutes. Remove from pan and set aside. Wipe the pan clean and warm the tortillas. Divide mushrooms among the tortillas. Top with pickled radishes, cilantro, avocado slices and a drizzle of your favorite hot sauce.