Supersize sausage casserole

A bit like the chilli from a couple of years ago, just for the record here is our recipe for sausage casserole, served at the WYC quiz and supper.

Serves 36 in total (same base for veggie and meat - just vary the sausages and stock). Around £2 a head, made with good quality sausages (50p each) and with plenty of bread to mop up.

Ingredients:
2.5kg onions
2kg courgettes
1kg carrots
2kg peppers (mixed)
1.3kg mushrooms (a wholesale box)
12 x 400g tins tomatoes
6 x 400g tins borlotti beans
seasoning to taste - we used 3 stock cubes, smoked paprika, mixed herbs, marmite, wholegrain mustard
72 sausages (we had 60 pork and 12 Quorn Cumberland-style)
Cornflour to thicken.

Method:
While cooking the veg as below, cook the sausages in the oven until browned. Allow to cool and then cut into 3 or 4 pieces each. It is fine to be a little pink in the centre as they are going to get cooked again in the casserole,
Chop the onions and cook slowly in a little oil plus paprika and herbs, until they start to turn translucent.
Chop and add the courgettes - they can be quite chunky as they'll get a long cooking time.
Grate the carrots and add to the onions and courgettes. Cover so that the steam condenses back into the pan.
Chop the peppers, again chunky, and add them to the mix.
Cook the mushrooms separately: layer them in a pan with a sprinkling of salt or 2 or 3 times, add a splash of water then cover and simmer until the mushroom shrink and lose water.
Add the mushrooms, with a slotted spoon, to the vegetables, and then add the tomatoes.

Make up 3 stock cubes with just enough mushroom water to dissolve (discard the rest), and also stir in a spoonful or two of marmite and a good dollop of mustard before mixing the whole lot into the casserole. Taste, and adjust as needed. We used 2 pork stock cubes (Knorr ones are really nice and smoky tasting) and one veggie one, and so here we started to keep the two casseroles separate.

Add the beans. Simmer for a while and then use some of the tomato/vegetable liquid to make up cornflour (mix to a paste with cold water, then add hot liquid, mix well and return to the pan, stirring thoroughly. We perhaps used 5-6 tbsp or a bit more, between the whole lot).
Add the sausages and simmer until they are thoroughly cooked.
Serve with crusty bread and butter. We allowed one 400g bloomer for 6 people (cut into 12 chunks), but could have got away with one per 7 people and still had some left.