1. Preheat the oven to 350 degrees. Rub the beets with 1/2 tablespoon of the olive oil and bake them in a 14 X 9 X 2-inch oiled baking dish, covered, until tender, about 1 hour.
2. Meanwhile, heat the remaining 1 tablespoon olive oil in a medium-size skillet, add the mushrooms and garlic, and cook, stirring, for 5 minutes.
3. When the beets are cool enough to handle, cut them in half and scoop out most of the pulp with a grapefruit knife or spoon, leaving a _ inch-thick wall of pulp adjacent to the skin.
4. Chop the scooped-out beet pulp and mix it with the mushroom mixture, bread crumbs, the Mint-Lime Sauce, and pepper.
5. Return the beet shells to the baking dish and pile the stuffing into them. Bake the stuffed beets, covered, for 20 minutes.