Slice bacon bacon into lardoons, about 1/2” thick. Fry bacon in a large skillet over medium heat until crispy; drain bacon on a paper towel, but reserve fat.
Thinly slice shallot; toss with 1/2 tsp sherry vinegar and set aside.
In large mixing bowl, whisk together dijon, 1 tsp sherry vinegar, a pinch of salt, a few grinds of black pepper and 1 tablespoon extra-virgin olive oil. Add 1 tablespoon reserved bacon fat; whisk to emulsify.
On a mandoline, thinly slice cauliflower and fennel. Roughly chop parsley. To the bowl with the vinaigrette, add the bacon, shallot, cauliflower, fennel, parsley and a pinch of salt; gently toss to combine. Shave cheese (I use a vegetable peeler) over the top and gently toss one final time. Serve immediately.