I adapted this excellent soup from Rick Bayless' "Mexican Kitchen", my main Mex cookbook.
Roast 1 medium brown onion and 1/2 head of garlic in oven. Dice onion and remove garlic from cloves.
Cut 750g-1kg rump steak into cubes. Brown in pan.
Put 2 litres beef stock, steak, 1/2 of the garlic and 1/2 of the onion into a soup pot with 1/2 tsp salt, 3 bay leaves, a big pinch of cloves, 1/4 tsp ground cumin and 1/4 tsp freshly ground black pepper. Bring to the boil and simmer gently for 1 hour.
Rehydrate 2 dried Ancho chillies in warm water for 30 mins. Puree with the rest of the onion, garlic and 1 x 400g can of diced tomatoes. If you don't have access to Mexican chillies, you'll have to work out what other kind of chilli to use. Just bear in mind that its soup and too much chilli will overpower the whole dish.
Slice 2 chorizos thinly and saute. Dry on paper towels to remove excess oil.
After 1 hour, add chilli mixture to soup pot, along with 2 diced carrots and another 400g can of diced tomatoes. Simmer for 10 mins. Add 2-3 potatoes, peeled and cubed. Simmer for 5 mins.
Add 2 zucchinis, cubed, the cooked chorizo, 1/2 can corn kernels (or better still - 2 ears of corn sliced to 2cm thickness), and a handful of chopped coriander leaves. Simmer for about 8 mins.
If the soup seems a bit thin, add 3 tsp cornflour mixed with water.
Serve with a dollop of sour cream on top (we didnt have any) and a wedge of lime. Very excellent.