Sausage Fondue Nachos

1 1/2 Tbs. unsalted butter

1 medium onion, halved and thinly sliced

1 sprig thyme

2 Tbs. white wine

8 oz. kielbasa

1 (7.2 oz.) bag sesame Pretzel Crisps

2 c. shredded Gruyere cheese

1 large tomato, diced

1/2 c. sour cream

2 Tbs. Dijon mustard

Melt butter in a large skillet over medium-high heat.  Add onion and thyme and stir.  Let onion cook without stirring about 5 minutes, or until dark brown.  Reduce heat to low, add a pinch of salt, and cook until onions are caramelized, about 20 – 30 minutes.  Raise heat to high, add wine, and scrape up any brown bits from the pan.  Cook, stirring, until liquid is nearly evaporated.  Transfer onions to a bowl and remove and discard the thyme sprig.

Meanwhile, preheat oven to 400 degrees.  Slice kielbasa very thinly, place on a baking sheet, and bake until crisp, about 10 minutes.  Remove from oven.

Layer half of the Pretzel Crisps on a small baking sheet.  Top with half the kielbasa, onions, cheese, and tomatoes.  Add another layer of Pretzel Crisps, kielbasa, onions, and cheese, and bake 5 – 8 minutes, or until cheese is melted.  While nachos are baking, stir together sour cream and mustard.

Remove nachos from the oven, place on a serving plate, and scatter with remaining tomatoes.  Serve with mustard sauce.