Rinse the beet greens using cold water and a colander to remove any grit or dirt. Strip the leaves from the stems then remove and discard any tough parts of the stems.
Finely dice the stems and set aside. Roughly chop the tender leaves.
Sauté the greens
Heat the olive oil in a medium skillet over medium heat. Add the onion and cook for 2-3 minutes or until they become translucent. Add diced stems and cook for another 2 minutes. Reduce the heat to medium-low then add garlic, stir, and cook for another minute before adding greens and red pepper flakes to the pan. Squeeze the juice of the lemon into the pan as well.
Cook until stems and greens are tender, about 5 more minutes, tossing occasionally. Season with salt, to taste. Add lemon zest to finish (optional).
Notes
The same process can be applied to other greens like spinach, kale, and collard greens to create quick side dishes at home.
Feel free to play around with the seasonings, substitute with your favorite flavors.