Choose avocados that yield slightly to gentle pressure but aren't mushy; if unripe, place in a paper bag with a banana for 1-2 days to accelerate ripening naturally.

Toast bread until golden and crispy but still slightly pliable, which creates the perfect textural contrast with creamy avocado while preventing sogginess from toppings.

Toss sliced avocado immediately with fresh lemon juice to prevent browning and add bright acidity that balances the richness of the toast.

Sauté shiitake mushrooms and pickled onions separately, then layer warm components onto the toast to create temperature contrast and allow flavors to meld beautifully.

Prepare the egg (fried, poached, or soft-boiled) as the final step and place it on top immediately before serving so the warm yolk can cascade over the toast for maximum richness.