Spicy Tomato Prawn Spaghetti - serves 4

I've been making variations of this pasta for a pretty long time now, and its always enjoyed but I've been thinking there are some ways I can make it better. One of these is the tenderness of the prawns, cooking them in the sauce for the whole time makes them tough and they lose nice juicy flavour that prawns usually have, this way of doing it gives the meal that little je ne sais quoi! The sauce for this pasta can be made in advance and kept in the fridge or freezer for anytime you need a quick fix plate of pasta!

Ingredients:

500g linguini or spaghetti 
300g fresh prawns (shelled) 
1 red onion 
2 cloves garlic
1 red chilli (with the seeds!)
handful of mushrooms 
half a red pepper 
200g tinned tomatoes
4 tbsp greek yogurt 
50g grated cheddar cheese 
1 lemon
1 courgette 
chorizo (amount is up to you)

Method:

The sauce for the pasta can be made in advance, but if you're not making this in advance, get the water ready t boil now. Roughly chop the red onion, garlic, chilli, mushrooms, and pepper. Fry the onion, chilli and garlic for around 5 minutes until it begins to go soft then add the vegetables. Once these are all soft add the tomatoes to the sauce and boil, (tomatoes are very acidic so for each 400g add a teaspoon of sugar - for this 200g only 1/2 tsp) then add the yogurt and cheese and stir well. This can either be boiled for sometime or immediately blended and set aside. Taste the sauce once it is blended, it may need more salt or pepper, or even a squeeze of lemon juice. 
  Dice the courgettes, (if you're in a hurry they're also nice grated) and chop the chorizo and fry both of these until the courgettes are cooked and the chorizo is crispy, put these in a bowl ready to add the pasta once its cooked. Again, if this is being in advance these vegetables can sit next to the sauce ready to be added and warmed through. Put the pasta in the pan with plenty of salt and simmer for the given time. While the pasta is cooking butterfly the prawns. It makes them open really nicely and curl around making them seem bigger and the dish look a little more professional. To do this have the back of the curve of the prawn facing you and carefully cut down to the vein opening them up but not halving them. (they can be butterflied with the belly facing up, but I like the curliness this adds)
  Once the pasta is cooked and drained add your desired amount of sauce, plus the courgettes and chorizo and heat it all through gently while you fry the prawns. 
Heat a frying pan over a high heat and add a dash of olive oil, then add the prawns and quickly squeeze in the juice of half a lemon, toss these about until they're cooked. Serve the spaghetti and top with some lemony butterflied prawns.