Colorful winter potluck dish

This dish garnered many positive comments at a potluck today. The original recipe comes from the cookbook Local Flavors: Cooking and Eating from America's Farmer's Markets by Deborah Madison. Here, I have adjusted the amounts of just about everything to make the dish for a larger group.

Sweet Potatoes Braised in Cider

Also good for winter squashes, perhaps yams, and carrots

4 medium-sized sweet potatoes, peeled and cut into bite-sized chunks (prepared weight is about 3 pounds)
4 Tbsp unsalted butter (for vegan version, use vegan margarine)
1 Tbsp finely chopped fresh rosemary
2 c or more of apple cider, enough to nearly cover vegetables in pot
salt and pepper if desired (I used none)
apple cider vinegar to taste (optional, I also used none)

Melt butter in a large pot, cook the rosemary on medium heat about 3 minutes to flavor the butter. Toss the vegetables in the butter, add liquid until vegetables are nearly covered. Cover pot with lid and bring to a boil. Turn heat down and simmer 20 to 25 minutes until vegetables are tender. If the juices have not reduced to a glaze yet, uncover and boil quickly on high heat until liquid reduces. Season with salt, pepper, vinegar to taste.