Heat the olive oil and quickly brown on all sides for 3 minutes. Drain away any excess fat, then add in the herbs and spices and mix through. Season with salt, add in the salsa and continue to cook for 5 minutes. Remove off the heat and stir in the chopped coriander.  Meanwhile, make the sour cream by mixing together the cream and juice of 1 lime to thicken. Also, smash the avocado and mix in a pinch of chill flakes, salt and lime juice to make the guacamole. When ready, cut the tortillas into small discs using a cutter or a knife. Heat a large frying pan with oil and fry the tortillas on both sides till crispy. Remove from the pan and stuff with the beef chilli filling, diced tomatoes and a drizzle of sour cream. Serve on a platter with the guacamole and sour cream on the side.