Additional toppings, all optional: black pepper, red pepper flakes, quality olive oil, hot sauce, greens, shaved radish, asparagus or carrots, toasted pumpkin or sunflower seeds, thinly sliced shallot or purple onion, sliced cherry tomatoes and so forth. Also, put an egg on it!
Toast your slices of bread well.
Slice the avocado in half, lengthwise, and remove the pit. Use a big spoon to scoop out the flesh. Put it in a bowl and mash it up with a fork. Mix in a squeeze of lemon or lime (optional).
Smash some avocado on top of your toast and top it with a light sprinkle of sea salt (mandatory!). Enjoy as-is or top with any of the listed ingredients above.
Mashed avocado is way better than sliced avocado here. I don't know why. It just is.