Wash the 2 cups of Brussels sprouts. You can slice a bit off the bottom of the Brussels sprouts if they are discoloured/ brown. Cut the Brussels sprouts into halves or quarters, depending on their size (small ones into halves, larger ones into quarters).
Place the Brussels sprouts into a steamer for 5-7 minutes, until they are bright green in colour and starting to become tender. If you don’t have a steamer, place into a pot with 1-2 inches of water and bring to a boil for 4-5 minutes. Drain away any water as needed.
While the Brussels sprouts steam, dice the 5 tbsp of onion.
Bring a pan up to medium heat and pour in the 1 tbsp of oil with the 5 tbsp minced onion and the 3 tbsp chopped walnuts. Sautee for 3-5 minutes, until the onion softens and is translucent.
Toss the Brussels sprouts into the pan and add the 2 tbsp balsamic vinegar and 2 tbsp maple syrup.
Sautee the Brussels sprouts for 3-4 minutes.