Mix the spices and half the oil in a bowl. Place steak and lamb steaks into separate bowls. Divide spice mixture among meat. Rub evenly over meat to coat. Refrigerate for 30 minutes.
To cook the meat
Preheat a char grill or barbecue on medium-high and cook the rump steaks and lamb leg steaks for 2 - 3 minutes on each side. Then transfer to a plate, and cover with foil. Rest for 5 minutes before serving.
To cook the vegetables:
Spray the onion and sliced peppers with the remaining oil. Cook on the char grill or barbecue, turning occasionally, for 5 minutes or until tender and lightly charred.
Cook tortillas for 30 seconds on each side or until beginning to char.
Arrange slices of lamb, beef, onion and peppers on a large serving board with salsa, guacamole, tortillas, sour cream and lime wedges.
For the salsa:
Mix all the ingredients in a bowl. Season with salt and pepper.
For the guacamole:
Mash the avocado in a small bowl, stir in coriander, lime juice and red onion, and season with salt and pepper.