Preheat oven to 350 degrees. Drizzle a little olive oil in the bottom of a glass baking dish. Prepare the peppers: Carefully slice off the tops and remove the seeds and trim the core off the tops if you want to serve them with the tops on. If the bottoms of the peppers are too bumpy, you may need to trim them down so they sit flat in the baking dish.

Drizzle a little olive oil in each pepper and bake for about 20 minutes while you prepare the filling.

Place the quinoa, the diced onion, and 2 cups water in a large pot with a lid. Bring to a boil, then reduce heat to low, cover, and cook on low for 15-20 minutes until quinoa is soft and fluffy.

Remove peppers from oven and spoon filling into each pepper. Place tops on each pepper if desired.

Bake stuffed peppers at 350 degrees for 15 minutes.

Let cool for a few minutes before serving. Add more salt and pepper if desired.