Cut stalks off fennel (save fronds). Shave the fennel and onion using a mandolin, or slice finely.
Place in a bowl. Add lemon juice and 1 ½ tbsp olive oil, salt and pepper. Toss.
Spread out on a plate "carpaccio" style. Drizzle with more olive oil, top with freshly grated parmesan then sprinkle with fennel fronds.
Serve immediately!
