Heat your olive oil over medium heat in a high sided saute pan. Add your onions, chillies, garlic and 1 tsp salt. Cook gently for about 20 minutes, stirring frequently. When you're happy with this base, turn up the heat and add the beef. Stir to combine. Add spices and tomato puree. Continue to stir fry until the meat has changed colour. Add the beef stock, tomatoes, sugar, oregano and the other 1 tsp salt. Bring to a simmer, partially cover then reduce the heat to low and cook for at least two hours. Cool completely.
Cut all of your tortillas in half and, in batches, place on a baking tray and grill until nicely browned and crisp (this will dry out the tortillas and improve flavour).
Line a 9", square, baking tin with greaseproof paper. Lay 4 halves of tortilla in the base. Spoon in an even layer of chilli, then sprinkle with an even layer of cheese. Continue until your tin is full. Top with the jalapenos and a little more cheese. Cover with foil and bake at 190°C for 1hr 15 minutes, removing the foil for the final 15.
Get stuck in. Serve with sour cream and coriander!