Grate the cabbage, cucumbers, and kohlrabi or chop them in a blender with rotating blades. You should get a coarse, crunchy crumble.
Mix the garlic, avocado, lemon juice, tahini, and olive oil, add salt and spices, and blend it into a purée using an immersion blender – this will be the dressing.
Mix the dressing with the salad and serve with pieces of matzo to scoop up the salad (similar to how corn chips are eaten with guacamole).