How to Make It
Preheat the oven to 350°. In a medium bowl, toss the bread with the butter and parsley and season with salt. Spread the croutons on a rimmed baking sheet and bake them for about 20 minutes, or until golden brown.
Season the onion slices with salt and pepper and lightly drizzle them with pure olive oil. In a large grill pan or skillet, char the onion slices over moderate heat until slightly softened and blackened in spots on both sides, about 18 minutes. Cut the charred onions into 1/2-inch dice.
In a large bowl, whisk the extra-virgin olive oil with the vinegar, shallots, ginger and garlic. Stir in the charred onions and season with salt and pepper. Add the mesclun and toss well.