When you just can't look another zucchini in the face, put it on a pedestal. Raw zucchini can be spongy, bitter and strangely sticky, so pamper it like Patricia Wells does here, by shaving it into delicate ribbons, then bathing them in a lemony marinade.
A trusted mandoline makes a big difference here -- and if you don't have one, you're better off opting for a vegetable peeler than a sharp knife. You want planks as thin as flower petals.
There will be leftover lemon salt. Swirl it into buttered pasta; dust it on blanched green beans; put a pinch on a dark chocolate cookie.
Combine the lemon zest and salt in a spice grinder, and grind into a fine powder. Transfer to a small jar and close the lid. (Store, sealed in the jar, in the refrigerator for up to 1 week. After that the lemon flavor will begin to fade.)
In a small jar with a lid, combine the lemon juice and 1/4 teaspoon Lemon Zest Salt. Cover with the lid and shake to blend. Add the oil and shake to blend.
With a mandoline, vegetable peeler, or very sharp chef's knife slice the zucchini lengthwise as thin as possible. Arrange the slices on a platter and pour the dressing over them. Tilt the platter back and forth to coat the slices evenly. Cover with plastic wrap and let marinate at room temperature for 30 minutes, so the zucchini absorbs the dressing and does not dry out.
Halve, pit, and peel the avocado, and cut it lengthwise into very thin slices. Carefully arrange the slices of marinated zucchini on individual salad plates, alternating with the avocado slices, slightly overlapping them. Sprinkle with the pistachio nuts. Garnish with the thyme leaves and flowers and fleur de sel. Serve.