Toast the walnuts in a dry skillet over medium heat for 3-5 minutes until fragrant and lightly browned, tossing occasionally. Allow to cool completely before chopping.
In a small bowl, whisk together lemon juice, vinegar (if using), Dijon mustard, salt, and pepper.
Slowly drizzle in the olive oil while whisking continuously to create an emulsion. Taste and adjust seasoning if necessary.
In a large salad bowl, gently combine the mixed greens, radicchio, shaved carrots, radishes (if using), and shallot (if using).
Just before serving, drizzle the vinaigrette over the salad and toss gently until all ingredients are lightly coated.
Sprinkle the crumbled goat cheese, toasted walnuts, and fresh herbs over the dressed salad.
Serve immediately on chilled plates for the most authentic French dining experience.
