Ingredients

• 1 large egg yolk
• 2 teaspoons Dijon mustard
• Kosher salt
• 1/4 cup olive oil
• 1/4 cup vegetable oil
• 4 teaspoons apple cider vinegar
• 1/2 teaspoon hot sauce
• Freshly ground black pepper
• 8 large eggs
• Kosher salt, freshly ground pepper
• 4 pieces focaccia or slices country-style bread, toasted
• 2 scallions, very thinly sliced
• 1/4 cup torn basil leaves
• 1/4 cup torn dill fronds
• 2 tablespoons 1/2-inch pieces chives
• 1/2 teaspoon finely grated lemon zest
• 1 teaspoon fresh lemon juice
• Olive oil (for drizzling)

Instructions

1. Combine egg yolk, mustard, and a pinch salt in a medium bowl. Anchor bowl by setting it inside a towel-lined saucepan, which will afford you 2 free hands—1 for pouring and 1 for whisking. Whisk until very smooth.
2. Combine olive and vegetable oils in a measuring glass and pour into yolk mixture, drop by drop at first, then in a slow steady stream as mixture stiffens, until all the oil has been added. Whisk in vinegar and hot sauce; season with salt and pepper. Thin mayo with water if needed, adding a teaspoonful at a time until just loose enough to fall off a spoon.
3. Gently lower eggs into a large saucepan of boiling salted water, and cook, maintaining an active simmer, 9 minutes. Immediately transfer eggs with a slotted spoon to a bowl of ice water and stir until cool enough to handle, about 1 minute. Drain, pat dry, and peel eggs. Tear eggs into large pieces and add to mayonnaise. Gently fold just to coat; season with salt and pepper. Spoon over bread.
4. Toss scallions, basil, dill, chives, and lemon zest in a small bowl. Add lemon juice, drizzle with oil, and season with salt. Toss to coat. Pile herbs on top of egg.