Mushroom and sauerkraut pierogi

Mushroom and sauerkraut filling

• 500 g sauerkraut
• 1000 g water
• 1 tbsp grapeseed oil
• 1 onion (approx. 150 g), cut into halves
• 500 g button mushrooms, cut into halves
• 1 ½ tsp sea salt, to taste
• ¼ tsp ground black pepper, to taste

Dough

• 250 g warm water, plus extra to seal
• 1 egg
• 2 tbsp grapeseed oil
• 560 g plain flour, plus extra to dust
• 1 - 2 pinches sea salt, plus extra to boil
• water, to boil

Topping

• 120 g salted butter, cut into cubes
• 1 large onion, diced
• sour cream, to serve
• fresh chives, finely chopped, to serve