Fold 1 slice roast beef inside each of 2 soft tortillas and sprinkle with cheese. Pack in the biggest compartment of the lunch box. Pack other compartments with guacamole, salsa, sour cream and other favourite toppings. Seal and send off to school.
For the speedy salsa:
1)Grate tomatoes on the largest holes of a box grater into a bowl all the way down to the skins. Discard the skins. Grate the onion into the tomato. Stir in olive oil. Season with salt, to taste.
2) Serve with coriander leaves on the side, or stirred in, if desired.
For the quickie guacamole:
1) Scoop the flesh from the shell with a spoon into a medium bowl. Squeeze the lime juice over the avocado and stir to coat evenly. Add the salt. Use a fork to stir and mash into a chunky guacamole. Stir in tomatoes or fruit, if desired.