Cut the tough top and bottom from kohlrabi. Using a peeler, or carefully with a paring knife, remove the tough outer layers from the bulb until only white flesh remains. Cut into thin matchsticks, about 2 inches long and 1/8" thick. Cut apple and Manchego into matchsticks of the same size. In a large bowl, toss with lemon juice to prevent apple from browning.

In a dry skillet over medium heat, toast walnuts for about 4 minutes while stirring. Remove from heat and add to salad. Toss with olive oil and parsley and season with salt and pepper to taste.