3 tablespoons mayonnaise
1 1/2 tablespoons fresh lemon juice
1 1/2 teaspoons grated onion
1 1/4 teaspoons coarse-grained Dijon mustard
1 1/4 cups shredded peeled broccoli stems
3/4 cup shredded peeled carrots
Combine mayonnaise, fresh lemon juice, onion and mustard in medium bowl; whisk to blend.
Add broccoli and carrots; toss to coat. Season slaw to taste with salt and pepper.
Refrigerate to blend flavors, about 20 minutes.