2 tablespoons extra-virgin olive oil, plus more for brushing
1 large onion, thinly sliced
Kosher salt and freshly ground pepper
1 thin baguette, sliced 1/4 inch thick
1 large garlic clove, halved
6 large eggs, at room temperature
1 tablespoon finely chopped chives
1 teaspoon white wine vinegar
24 white anchovy fillets or pickled herring pieces—drained, patted dry and
Heat 1 tablespoon of oil in a skillet. Add the onion; cook over moderately low heat, stirring occasionally until browned, 1 hour. Season with salt and pepper.
Preheat the oven to 300°. Lightly brush both sides of the bread slices with olive oil and arrange on a large baking sheet. Bake the crostini for 5 minutes, or until crisp, but not golden. Immediately rub 1 side of each crostini with the garlic. Let cool on the baking sheet.
Meanwhile, prepare an ice water bath. Bring a small pot of water to a boil. Add the eggs and return to a boil, then boil for 7 minutes. Immerse the eggs in the ice water bath until completely cool, then peel and transfer to a medium bowl. Lightly mash the eggs with a large fork. Gently stir in the chives, vinegar and the remaining 1 tablespoon of olive oil. Season with salt and pepper.
To assemble, top each crostini with the onion, followed by the egg salad and a piece of anchovy.
The soft-boiled eggs can be refrigerated overnight. The crostini toasts can be stored in an airtight container overnight. Mix the egg salad and assemble the crostini up to 30 minutes before serving.