1. Prep and Blanch the Brussels Sprouts:
Bring a large pot of water to a boil. Cut the Brussels sprouts in half if they’re small, or into quarters if they’re larger. Add to boiling water and cook for 3–5 minutes, just until tender-crisp. Drain and set aside.

2. Cook the Bacon:
In a large, heavy skillet over medium heat, cook the bacon pieces until browned but not overly crisp (about 3–6 minutes). Use a slotted spoon to transfer bacon to a paper towel-lined plate. Discard all but 1 tablespoon of bacon fat from the pan.

3. Sauté the Onion:
Add olive oil to the pan along with the reserved bacon fat. Add the diced onion and cook over medium heat, stirring often, until softened (about 4 minutes). Avoid browning the onions. Stir in the herb sprigs, salt, and pepper.

4. Cook the Brussels Sprouts:
Raise the heat to medium-high. Add the blanched Brussels sprouts and cook for about 3 minutes, stirring occasionally, until heated through and lightly caramelized. Discard the herb sprigs.

5. Finish and Serve:
Return the bacon to the pan and add the reserved thyme or savory leaves. Drizzle with lemon juice, if using, and toss to combine. Serve warm.