Prepare sprouts and potatoes. Chop the stem off the brussels sprouts and remove outer leaves. Chop in half and rinse thoroughly. Set aside to dry. Chop potatoes to the same size as brussels sprout halves.
Preheat oven to 375º and line two baking sheets with parchment paper.
Spread brussels sprouts on one sheet and potatoes on the other.
Whisk together balsamic, mustard, olive oil, maple syrup, herbs, pepper, and salt. Pour half over the brussels sprouts and half over the potatoes. Mix them up to coat evenly.
Place the potatoes in the oven and bake 10 minutes. After 10 minutes have passed, add brussels sprouts and cook 30-40 minutes until everything is tender.