Preheat oven to 375º F. Grease a pie dish or other small baking pan with olive oil or cooking spray.

Peel the skin of the celery root and chop it into small 1/2-inch cubes.

In a small bowl, toss the celery root with 1/2 tablespoon olive oil and a dash of salt. Pour the celery root onto the pie dish and bake for 15 minutes.

Rinse the cauliflower and chop the florets into small pieces. Place them in a microwave-safe bowl and microwave on high for 4 minutes. Check the cauliflower and see if it is cooked. If it still looks raw, microwave it at 1-minute intervals until the cauliflower is cooked through or easily pierced with a fork.

When there are only several minutes left in the baking, add the minced garlic to the celery root and stir everything together. Continue baking the celery root until it can be easily pierced with a fork.

When the celery root is done baking, combine it with the cooked cauliflower. Using an immersion blender or food processor, purée the vegetables until smooth. Mix in the chopped sage and season with more salt and pepper to taste.

Heat the other 1/2 tablespoon of olive oil in a sauté pan over medium-high heat. Place the onions in the sauté pan.

When the onions start to brown, add in the beet greens and sauté for about 3-4 minutes. Season with salt and pepper.