Best Bangers and Mash with Onion Gravy

Sausage and mashed potatoes - BORING - or so I thought.  There is a reason that this is the number one comfort food in Great Britain!  It is delicious - soul satisfyingly delicious.   When my butcher had a special of any sausage $1.99 a lb.(usually $4 -$5+ ) I bought my favorites - parsley and provolone, broccoli rabe, Italian, and something that I normally would never buy - bangers.  Well all of the cold and snow brought out the urge for some great comfort food, European style!  I perused many recipes and eventually came up with a hybrid of many that sounded interesting.  I am so happy with the results and I am now a bangers and mash fan!  I absolutely loved the caramelized onion gravy!  Great pub grub! 

1 lb. bangers
2 medium onions, halved, peeled and thinly sliced
1 1/2  tbsp olive oil
1 1/2 tbsp butter
1/2 tsp. thyme
1 tsp sugar
1 tsp balsamic vinegar
1 14.5 oz. can beef stock
2 tsp corn starch
2 tsp cold water
Salt and black pepper

Heat oven to 350 degrees.  Add bangers to an oven safe dish and baked in preheated oven until cooked through.  Remember to turn them during cooking so that they brown uniformly. 

Meanwhile, heat the olive oil and butter in a heavy saute pan.  Add the onions, season with thyme, and cook over low heat (stirring every so often) until softened and beginning to caramelize.  Stir in the sugar and balsamic, cover the pan, and cook on low for 5 minutes.  Next add the beef stock and bring to a boil (uncovered).  Whisk together the corn starch and water.  Add to the onion gravy.  Stir and boil until it becomes slightly thickened.  Serve immediately with mashed potatoes.  Enjoy!