Ingredients
1 baguette (8 ounces), cubed
6 tablespoons olive oil
Coarse salt and ground pepper
1/4 cup red-wine vinegar
1 tablespoon Dijon mustard
10 ounces white mushrooms, trimmed and thinly sliced
10 ounces baby spinach
1 medium red onion, halved and thinly sliced
Preparation
Preheat oven to 450 degrees. On a large rimmed baking sheet, toss bread with 2 tablespoons oil; season with salt and pepper. Bake, tossing occasionally, until toasted, 4 to 6 minutes. (To store, keep croutons in a resealable bag, up to 1 week.)
In a large bowl, whisk together remaining oil, vinegar, and Dijon; season with salt and pepper. (To store, refrigerate dressing, up to 1 week.)
Toss mushrooms with dressing; let stand 5 minutes. Add spinach, onion, and croutons to bowl; toss, and serve immediately.
