1. In a cheesecloth bag, tie cinnamon, cloves and all-spice and arrange in 5- quart Dutch electric oven with sugar and cider vinegar and cook at low heat for about 5 minutes.
2. Heat the cider by setting the control at WARM.
3. Take out the spice bag just in a time before serving. Arrange thinly sliced lemon slices over it.
4. Serve the hot mulled apple cider in mugs.