POUND THE GARLIC and the salt in a mortar until completely smooth. Stir in the lemon juice, lemon peel, fennel seeds and olive oil to make a tart, lemony vinaigrette. Thinly slice the mushrooms, carefully dress them with a few tablespoons of the vinaigrette, and season them with plenty of freshly ground black pepper. Lay a damp kitchen towel or a piece of plastic wrap directly over them to keep them from browning, and set aside for 1 hour to marinate. Trim the fennel bulb and cut it into quarters. Remove most of the core; then slice it lengthwise, very thinly, leaving the pieces joined together. Dress it with most of the remaining vinaigrette and half the herbs, and season with salt and pepper. Add the rest of the herbs to the mushrooms. Layer the mushrooms, cheese and fennel on each plate and spoon the remaining vinaigrette over the top.