Wash collard greens under running water, remove tough stems, and chop leaves into bite-sized pieces.

In a large skillet over medium heat, heat olive oil and sauté diced onion until translucent (about 5 minutes). Add minced garlic and cook for an additional minute.

Stir in chopped collard greens and vegetable broth. Cover and let simmer for about 10 minutes until tender.

Remove the lid and add lemon juice and red pepper flakes. Stir well and adjust seasoning if necessary.

Cook uncovered for another 5 minutes if you prefer drier greens, then serve warm.