Created by Galley_Wench on November 19, 2011
Step 1: To prepare potatoes; cook the potatoes in water until tender, about 20 minutes. Once tender, thoroughly drain the water. Add sour cream, butter and prepared mustard; mash until smooth and creamy.
Step 2: While potatoes are cooking; prepare the sausages by pricking them several times with a kitchen fork. In sauce pan, bring the beer (or water) to a simmer over medium heat. Add the sausages and poach for 5 minutes. Removes sausages from pan and discard beer/water.
Step 3: Heat oil and mustard seed in large skillet over medium heat. Add the onions, sausage, salt and pepper. Cook until onions are tender and sausages are light golden brown, about 5-6 minutes (stirring often to avoid scorching the onions). Remove sausages, slice into thirds and place in a casserole.
Step 4: Add flour to pan, stirring until well combined. Stir in sugar, balsamic vinegar and thyme; cook for 2 minutes. Pour in beef broth; bring to the boil and cook for 5 to 10 minutes until gravy thickens. Pour onion gravy over sausages; top casserole with mashed potatoes and sprinkle french fried onions on the top.
Step 5: Just before serving, bake uncovered at 350 degrees fahrenheit for about 25 minutes until top is golden brown.