Bring a large saucepan filled with salted water to a boil over high heat. Prepare
a bowl filled with ice water and set it nearby.
Reduce the heat to maintain an active simmer and gently lower the eggs
into the water; cook them for 8½ minutes. Immediately transfer the eggs
with a slotted spoon to the ice water.
When the eggs are cool enough to handle, pat them dry and peel them.
Chop the eggs into large pieces and add them to a medium-sized
bowl, along
with the mayo, scallions, and garlic. Gently toss the eggs to coat in the mayo
mixture. Season with salt and black pepper to taste. Set aside.
In a small bowl, toss the basil, dill, parsley, and red pepper flakes. Add the
red wine vinegar, drizzle the mixture with oil, and season with flaky sea salt.
Toss to coat.
Spread 1 teaspoon of the mustard onto each slice of toasted bread. Spoon
the eggs over the bread. Pile the herb mixture on top of the egg toast and
serve.