Heat oil in an extra-large skillet over medium-high heat. Add beets and cook and stir for 5 minutes or until just tender. Add mushrooms, garlic, and ginger. Cook and stir for 4 minutes or until mushrooms are golden. Stir in chard and broth. Bring to boiling; reduce heat. Simmer, uncovered, for 1 to 2 minutes or until chard is tender. Remove from heat and stir in salt, pepper, and cilantro. Serve over polenta and garnish with additional cilantro.