Preheat oven to 400 degrees.
On two baking sheets, place all of the prepped veggies having already tossed them with oil.
Season with salt and pepper.
Roast until golden and tender. Different veggies may cook at different rates and also depend on how large you cut them. They should all pierce easily with a fork and have slightly browned, caramelized edges
While they are roasting, place all but 1/4 C of the cranberries in a sauce pan. To that, add the sugar and water. Cook on low heat for 10 minutes. Raise the heat to medium and cook for another 10 minutes until they start to pop and burst. Add in the remaining whole cranberries. Cook for another few minutes. Allow to cool slightly.
Fold the sour cream and horseradish into the warm, cooked cranberries. Place into a serving dish. Ideally, it would be best to refrigerate for a few hours but you could certainly serve it now.
Remove the veggies from the oven and serve immediately.