In a skillet, heat 1 tbsp oil, then cook your sliced kielbasa until browned. Remove from pan and set aside.
To the same pan, add 1 tbsp butter/margarine and 1 tsp flour. Whisk this together and let cook for 1 minute.
Slowly add in chicken broth and mustard. Simmer about 3-5 minutes until thickened.
While the gravy is simmering, make the instant mashed potatoes according to package directions.
Steam corn in the microwave.