Start this recipe by preparing the meat. Break up the beef stock cube in a bowl and mix with the cracked pepper, spices and olive oil. Rub the marinate all over the beef on both sides and allow to sit for 30 minutes. When ready to cook, heat a large griddle pan with a little oil and seal the meat quickly on both sides. Reduce the heat and cook to your liking. Meanwhile, prepare the guacamole by blitzing all the ingredient together in a processor till smooth. When the meat is cooked, allow to sit for 5 minutes then slice up thinly. Place into a bowl and mix in the mild salsa. To put the dish together, heat up the refried beans. Lay out the 2 wraps and spread with the guacamole. Spoon over the refried beans then cover with the salsa beef. Cover with some salad leaves and wrap up tightly. Place onto a hot dry pan and quickly brown the wraps on both sides. To serve, cut the wraps in half and serve on 2 slate boards with sour cream in small bowls on the sides.