Most bacon-wrapped Brussels sprouts recipes call for holding everything together with toothpicks, but we skip that step. Setting the bacon seam-side down on the baking sheet makes it seal in the hot oven. The maple syrup glaze helps to make each bite sweet and caramelized.
Preheat the oven to 400ºF. Trim the stem ends from the Brussels sprouts, and halve lengthwise. Put them in a medium bowl, and toss with 1 teaspoon salt.
Lay the bacon strips next to each other on a work surface. Brush liberally with about 1/2 the maple syrup, then halve crosswise. Wrap each Brussels sprout half with 1 strip of bacon, syrup-side out, so the seam is on the flat side. Place the sprouts seam-side down on a rimmed baking sheet, leaving a bit of space between them. Brush them with a bit more syrup, and grind a little black pepper on top. Roast, rotating the baking sheet halfway through, until the bacon is crisp and the sprouts are tender when pierced with the tip of a knife, about 30 minutes.
Meanwhile, mix the mayonnaise, most of the lemon zest and all the lemon juice in a small serving dish. Sprinkle the remaining lemon zest on top. Put about 1/2 cup maple syrup in a second small serving dish, and stir in as much black pepper and crushed red pepper flakes as you like.
Transfer the sprouts to a platter, and serve with the lemon mayonnaise and peppered maple syrup, for dipping.