Cook the quinoa according to the instructions on the package. (Quinoa can be made 1 day in advance to cut down on cooking time)
Preheat the oven to 400 degrees.
Heat a saute pan over medium heat. Once hot, add the oil. Saute the onion, garlic, celery, carrots, and oregano until the vegetables soften. Crumble in the beef and saute until browned and no longer pink while breaking it up into smaller pieces. Season with salt and pepper.
Stir in the tomatoes and low simmer until the quinoa is done cooking. Then remove from the heat and stir in the quinoa and egg. Top with cheese and bake in the oven for about 15 to 20 minutes. Let sit for 5 minutes before portioning.