Cut the shoots from the fennel and discard, reserving a good handful of green fronds. Chop these and toss them into a bowl. Peel the fennel bulbs, halve, core, and slice paper-thin, using a mandolin if you have one. Add to the bowl. Grate over the zests. Squeeze lemon juice over, to taste. Add the pine nuts. Drizzle over oil, to taste. Season with salt and pepper. Toss, taste and adjust the seasonings, and serve immediately.