Preheat broiler to hot. Put walnuts in a bowl and cover with boiling water. Let stand 1 minute, drain and shake dry. Toast under broiler 3-4 minutes until golden (watch carefully so they don't burn). Sprinkle with sea salt, toss and cool.
Put the baguette slices under broiler and toast one side until lightly golden. Remove and rub toasted side with cut garlic. Allow to cool a few minutes and turn over and place chevre slices on untoasted side. Broil 2 minutes, or until chevre browns slightly.
For the dressing, mix oils, vinegar and garlic together and season with salt and pepper.
Toss the mesclun, onion, and toasted walnuts together. Place on a large platter and top with chevre croutons. Drizzle with the dressing. Serve while croutons are still warm.