Using a mandolin or knife, thinly slice the cabbage, fennel, and apples, and place them in a large mixing bowl. Finely chop a handful of fresh dill and add it ot the mixing bowl.
Place all of the dressing ingredients in a mixing bowl or glass jar and mix until well combined. Stop to taste and adjust seasoning. If you need it to be thicker, add a little more yogurt; if it is too thick, add up to 2 tbsp of water.
Pour the dressing over your salad and massage until the dressing is well incorporated, and serve!
Storage Instructions: Store this salad in an airtight container in the refrigerator for up to 2 days, as the cabbage and fennel stay crisp longer than tender greens. For the freshest texture, store the dressing separately and toss just before serving.