Trim the ends off each sprout, then cut in half through the root end. Place cut side down on a cutting board, then slice.
Place the apple on a cutting board. Slice. To the large bowl of shredded Brussels sprouts, add baby kale, apple matchsticks,Pecorino, and almonds.
Combine extra virgin olive oil, the juice of 1 lemon, shallot, Dijon, garlic clove, Kosher salt, and freshly ground black pepper in a glass jar with lid. Place the lid on top, shake vigorously.
Drizzle as much of the lemon garlic vinaigrette on top of the salad as you like.
Toss the salad to thoroughly coat, then taste and adjust seasoning. Serve with a pinch of flaky sea salt on top.