Preheat oven to 400 degrees. Cut Brussels Sprouts, red onion and butternut squash into bite size pieces. Try to make them all similar sizes to allow for even cooking.
Place all veggies, including tomatoes, into a roasting dish. Drizzle with olive oil and sprinkle with salt and pepper, oregano and minced garlic.
Roast veggies for 30-45 minutes, depending on how big the pieces are. You'll know your veggies are done when they are fork-tender, meaning you can easily pierce a piece with a fork. Be sure to toss the veggies at least once when roasting.
Store the vegetables in a glass container with a tight fitting lid for 5-6 days in the refrigerator. Gently reheat them on the stove top with a little bit of oil over medium heat.