Miso udon noodle soup

Name: Miso udon noodle soup
Prep time: 10 min
Cook time: 1 h
Total time: 1 h 10 min
Cuisine: Japanese
Ingredients: 400 g tofu; 2 tbsp soy sauce; 2 tbsp sesame oil; 1 tbsp sunflower oil; 1 onion (sliced); 2 cloves garlic (chopped); thumb-sized piece ginger (peeled and chopped); 1 red chilli (deseeded and chopped, optional); 2 tsp miso paste; 1.5 litre vegetable stock; 2 carrots (thinly sliced); handful green beans (topped and tailed and chopped in half); 1 pak choi vegetables; 300 g pre-cooked udon noodles; salt and pepper (to taste); 4 spring onions (chopped); 1 tbsp black sesame seeds