Pre-heat the oven to 220ºC/200ºC fan
Finely chop the red onion.
Heat the olive oil (1 tsp) in a large pan, add the red onion and chopped chorizo (130g) and cook on a low heat for 5 minutes stirring regularly to avoid burning.
Add the arborio rice (300g) and cook for a further minute, stirring regularly.
Add the red wine (150ml), chopped tomatoes (400g can), chicken stock (400ml) and thyme and bring to the boil.
While the risotto is coming to the boil, roughly chop the asparagus (so each one is in about three pieces).
Once the risotto is bubbling, add the asparagus, put the lid on and put into the oven for 10 minutes.
After 10 minutes, add the frozen peas (125g) and stir. Return to the oven for a further 8-10 minutes until the rice is just soft but still has a little bite to it - you may want to check the risotto occasionally to ensure that it's not too dry. If it looks dry before the rice is fully cooked, add a little more water and give it a stir.
While the risotto is cooking, finely grate the manchego cheese (50g).
Once the rice is cooked, remove from the oven (don't forget the hot lid!), remove the sprigs of thyme and stir in the grated cheese - you may also want to add a little salt to your taste. Personally I choose not to as there's plenty in the other ingredients for my tastes.