How to Make It
In a large glass or stainless-steel bowl, whisk together the vinegar, Dijon mustard, salt, and 1/4 teaspoon black pepper. Add the 1/3 cup oil slowly, whisking.
Heat the broiler. Put the baguette slices on a baking sheet and brush the tops with the remaining 1 1/2 tablespoons oil. Broil until lightly browned, about 2 minutes. Remove the baking sheet from the oven. Turn the slices over and top each one with a slice of goat cheese. Broil until the cheese is soft and warm, about 2 minutes. Sprinkle a little pepper over each croûte.
Meanwhile, toss the spinach and radicchio into the dressing. Put the salad on plates. Top with the trout and the goat-cheese croûtes.
Use romaine lettuce instead of spinach.
Add a handful of frisée to the spinach and radicchio.