Pork stew

Name: Pork stew
Prep time: 25 min
Cook time: 1 h 35 min
Total time: 2 h
Cuisine: European, British
Ingredients: 1 tbsp rapeseed oil; 2 onions , halved and sliced; 3 celery sticks , thickly sliced; 2 bay leaves; 1 tbsp picked thyme leaves; 500g lean pork fillet , cut into large chunks; 2 tsp English mustard powder; 4 large garlic cloves , grated; 2 tbsp spelt flour; 4 tbsp cider vinegar; 800ml bouillon or chicken stock; 1 Granny Smith apple, peeled, cored and cut into chunks; 2 leeks , thickly sliced; 4 carrots , cut into chunks; 140g spelt flour; 1 tsp baking powder; 1 tsp English mustard powder; 2 tbsp finely chopped flat-leaf parsley; 1 tbsp picked thyme leaves , plus a few sprigs to garnish; 2 tbsp bio yogurt; 2 tbsp rapeseed oil