Prepare the collard greens by rinsing and stripping the leaf from the stem.
Place the water and the ham hock in a large pot with a tight-fitting lid. Bring to a boil. Lower the heat to very low and simmer covered for 30 minutes.
Add the collards and the hot pepper flakes the pot. Simmer covered for about 2 hours, stirring occasionally.
Add the vegetable oil and simmer covered for 30 minutes.
Keyword 5 ingredients or fewer, budget-friendly, dairy-free, entertaining, freezer friendly, gluten free, make ahead, one-pot, side dish, weeknight favorites