Preheat your oven to 375°F (190°C).
In a skillet, sauté chopped onions in olive oil until golden brown.
Mix mashed potatoes, sautéed onions, and ¡Yo Quiero! Bean Dip in a bowl. Season with salt and pepper.
Roll out the puff pastry sheets and cut them into squares.
Place a spoonful of the potato and bean mixture onto each square.
Fold the pastry over the filling to create a triangle and press the edges to seal.
Brush the knishes with the egg wash.
Bake for 15-20 minutes or until golden brown.