Egg Salad Tartines With Mixed Herbs

Name: Egg Salad Tartines With Mixed Herbs
Ingredients: 1 large egg yolk; 2 teaspoons Dijon mustard; Kosher salt; ¼ cup olive oil; ¼ cup vegetable oil; 4 teaspoons apple cider vinegar; ½ teaspoon hot sauce; Freshly ground black pepper; 8 large eggs; Kosher salt, freshly ground pepper; 4 slices country-style bread, toasted, or focaccia; 2 scallions, very thinly sliced; ¼ cup torn basil leaves; ¼ cup torn dill fronds; 2 tablespoons ½-inch pieces chives; ½ teaspoon finely grated lemon zest; 1 teaspoon fresh lemon juice; Olive oil (for drizzling)