Preheat your oven to 425 °F (220 °C). Line a rimmed baking sheet with parchment and set a wire rack on top for better crisping.
Trim the woody ends off the asparagus by bending each stalk until it snaps naturally (that point marks the tender part). Place asparagus in a bowl, drizzle with olive oil, sprinkle sea salt and black pepper, and toss until evenly coated.
Divide the asparagus into 8 bundles, each bundle containing 3 stalks. Cut each bacon slice in two lengthwise (to make narrower strips), then wrap one strip around each bundle tightly, seam-side down. Place the bundles spaced on the wire rack.
Bake on the middle rack for 12 minutes. After 12 minutes, flip each bundle with tongs so the bacon underside becomes top. Continue baking for another 4 minutes.
While the bundles bake, whisk together the Dijon mustard, whole grain mustard, honey, garlic powder and lemon juice in a small bowl until smooth and glossy.
After the 16 minutes of baking, remove the bundles briefly from the oven. Brush each with about half of the glaze, then return to oven and broil on high for 1–2 minutes — watch closely so the bacon glaze caramelises but doesn’t burn.
Remove from oven and brush any remaining glaze lightly over the top. Let rest for 1-2 minutes (this helps the glaze stick). Serve immediately while bacon is crisp and asparagus still has a slight snap.