For the taquitos, heat the olive oil in a large saucepan over a medium heat. Add the onion and garlic and fry until softened.
Add in the steak and fry for two minutes, until the meat starts to brown.
Add the oregano, cumin, sugar and tomato purée. Season with salt and freshly ground black pepper, stir well and leave to cook for a further minute.
Add the beef stock, bring to the boil and reduce the heat to simmer for a further 5-6 minutes, until the sauce thickens and the meat is cooked through.
Add the coriander and stir in.
Fill the centre of each flour tortilla with the beef mixture and roll each up like a big cigar. Place two onto each of four plates.
For the dressing, place the soured cream, cayenne pepper, warm water and chives into a bowl and mix well.
To serve, drizzle the dressing over the taquitos and serve with a lemon juice-dressed salad of your choice.