Add chopped potatoes to a large pot, cover potatoes with water. Bring water to a boil, cover and cook until tender, about 20 minutes. Drain the water from the potatoes, leave the potatoes in the pan.

While potatoes boil, heat skillet over medium heat, add olive oil. Using a fork, prick sausage links in a few places. Place sausage links in the pan. Cook and turn until sausage is evenly browned and juices run clear.

While sausage cooks, slice onion into thin slices

Remove sausage and drain on a paper towel

Add onions to skillet, stir until onions start to brown, but still have a crunch.

Heat gravy in a sauce pan over medium heat.

When potatoes are fork tender, add butter and milk mash until they are smooth and creamy. Add more milk as needed. Season with salt, pepper, and mustard, to taste

Scoop mashed potatoes onto plate, add sausage link and onions. Drizzle with gravy.