Some side dish recipes for a rib roast dinner are horseradish mashed potatoes and roasted white potatoes and asparagus. Food Network offers both recipes as part of complete rib roast dinner recipes.
For horseradish mashed potatoes, peel five Yukon Gold potatoes and cut them into chunks. Set them in a pot and cover with cold salted water by 1 inch. Bring the water to a simmer and cook for 20 minutes until the potatoes are tender. Combine 1/2 cup of butter, 1/2 cup of heavy cream, 1/2 cup of buttermilk and 2 1/2 tablespoons of prepared horseradish in a small saucepan and simmer over medium heat. Drain the potatoes, set them back in the pot, mash with the butter cream mixture and season with salt and pepper.
To make roasted potatoes and asparagus, add 3 pounds of skin-on potato quarters to the roasting pan with a rib roast after the roast has been cooking for about one hour. After 30 minutes, drain the oil from the potatoes and drizzle it over 2 bunches of asparagus spears spread out on a baking pan. Transfer the potatoes to the pan with the asparagus, set the pan in the oven and roast for about 15 minutes at 350 F.