Preheat oven to 400 degrees. Take puff pastry out of the box and bring to room temperature.
Drizzle 1 tablepsoon olive oil in a pan and place over medium-low heat. Add diced onion and sauté until golden.
In a small bowl, whisk 1 egg; set aside
Once puff pastry is room temperaure, cut into 4 sections big enough to fit the sausage links. Spread onion on the pastry square along with the sausage link and roll. Pinch together well. Brush each roll with egg then slice them up into bite size pieces, about 1 inch. Place on baking sheets and bake for 15-20 minutes until golden brown. Remove and serve with mustard. Best to let these cool slightly before enjoying!
