Southern-style collard greens get their signature richness from being cooked with ham hocks or bacon. For a vegetarian version that achieves the same depth of flavor, use a Parmesan rind instead. (It contains umami, the savory taste also found in cured meat.) The rind will hold its shape as the greens simmer, so you can remove it from the pot in one piece when done. Try adding a rind in our recipe for braised collards.