Remove stems from lacinato kale.

Massage lemon juice into kale leaves in a large bowl for 2-3 minutes.

Let kale marinate for 5-7 minutes.

Prepare salad dressing: Combine olive oil, Dijon mustard, and balsamic vinaigrette in a jar.

Shake the jar vigorously until the dressing emulsifies.

Season the dressing with salt and pepper to taste.

Roughly chop the marinated kale into bite-sized pieces.

Add the chopped kale back to the bowl.

Add thinly sliced Brussels sprouts, cheese, and toasted pecans to the kale.

Pour the dressing over the salad.

Toss all ingredients together to coat evenly.

Serve immediately.