01 - Place the eggs in a saucepan and cover with cold water by 1 inch. Bring to a rolling boil over medium-high heat, then cover the pot, remove from heat, and let stand for 9 to 10 minutes. Transfer the eggs to a bowl of ice water to cool completely before peeling and slicing into rounds.
02 - Toast the bread slices in a toaster or on a skillet over medium heat until golden brown and crisp on both sides.
03 - Halve the avocado, remove the pit, and scoop the flesh into a mixing bowl. Add the lemon juice, salt, and black pepper. Mash with a fork until the mixture is creamy but still retains some texture.
04 - Divide the mashed avocado evenly and spread it over the warm toasted bread slices, pressing gently to adhere.
05 - Arrange the tomato slices over the avocado layer, then top with the sliced hard-boiled eggs.
06 - Drizzle with olive oil if using, and sprinkle with additional salt, pepper, fresh herbs, and crushed red pepper flakes to taste. Serve immediately while the toast is still warm.