Using a vegetable peeler or mandoline, shave the zucchini into long, wide ribbons, turning the squash, if necessary, to ease shaving. Discard the seedy core. Put the zucchini into a colander set inside a bowl, sprinkle with salt, toss, and drain for 30 minutes. Discard the liquid.
Whisk together the olive oil, lemon juice, mustard, and pepper in a serving bowl. Add the zucchini, onion, frisee, and radishes. Toss to combine. Sprinkle with almonds, basil, and Manchego cheese, and serve. Can be stored, covered, in refrigerator for up to 3 days.