Preheat oven to 350F

Arrange the bacon on a baking sheet and bake until starting to get crisp. Cut the apples into thin wedges and add to the pan, tossing in some of the bacon grease. Scatter the fennel seeds on the pan as well. Roast until the bacon is crisp and the apples have started to soften and caramelize. Let cool slightly.

Core the radicchio and cut it into thin wedges or slices, making sure none of the pieces are too big. Core and thinly slice the fennel, and slice the celery on an angle. Put all the veggies, along with the watercress, into a wooden salad bowl. Season with pepper.

Put the dressing ingredients in a jar and use an immersion blender to emulsify. Taste to adjust any of the flavors. Lightly dress the salad.

Give the bacon a rough crumble, and add to the salad, along with the apples. If a little bacon grease comes along with, that's not necessisarily a bad thing ;) Drizzle with more dressing, and serve.