4 medium Earthbound Farm Organic Jewel or Garnet Yams (peeled and sliced 1/4-inch thick)
1 medium sweet yellow onion (cut in half through the stem end and thinly sliced crosswise)
1/4 cup extra-virgin olive oil
1/4 cup unsalted butter (1/2 stick, cut into 4 pieces)
2 tablespoons Sea salt
2 teaspoons fresh sage or thyme leaves (chopped)
  freshly ground pepper