3 fennel bulbs, trimmed, cored, and sliced thinly (with mandoline) |
1 large red onion, thinly sliced |
1/4 cup extra virgin olive oil |
6 tablespoons fresh lemon juice (from '1 1/2 lemons) |
2 teaspoons balsamic vinegar |
2 teaspoons dijon mustard |
1/2 teaspoon kosher salt |
1/2 teaspoon black pepper |
1 large bunch arugula, well washed, dried, and torn into bite-size pieces |
shaved parmesan cheese (to garnish) |