Thai Noodle Soup with Chicken

Name: Thai Noodle Soup with Chicken
Prep time: 5 min
Cook time: 40 min
Total time: 45 min
Cuisine: Thai
Ingredients: 1 kg pack of chicken thighs ((£3.14)); 50 g spring onions, thinly sliced ((£0.59)); 4 tbsp red Thai paste ((£2.40/2)=(£1.20)); 2 tbsp peanut butter ((£1.09/10)=(£0.10)); 400 ml (1 can) of coconut milk ((£0.85)); 200 g spaghetti ((£0.28); 2 bulbs of pak choi, sliced lengthwise into quarters ((£1.10)); Fresh coriander ((£0.60)); 1 lime, cut into wedges ((£0.25)); ½ tbsp olive oil; 1.4 litre chicken stock (2 cubes); 1 tbsp tomato puree; Salt & Pepper; Optional: 1 tsp fish sauce