Gather your mis en place; get together all of the equipment needed for the recipe and gather your ingredients.

Cut the onion in half, from root to tip. Peel off the first layer of skin, and cut off the tip of the onion. Make slices about 1 cm apart in the onion from the tip almost to the root, leaving the root intact to hold the onion together. Turn the onion and slice across your slices, dicing the onion.

Remove the stem from the iceberg by pushing the stem into the lettuce, then twisting and pulling it out. Cut the lettuce into 4, then slice across the shred it.

Cut the tomatoes into quarters and use the spoon to scoop out the seeds. Slice the flesh into strips, then cut across into dice.

Cut the avocado in half around the stone, then scoop the stone out. Use a spoon to scoop the flesh of the avocado out, and then slice across into cubes.

Crumble the cheese.

Separate the leaves of the cilantro from the stems and discard the stems.

Measure out the taco seasoning, garlic powder, and salsa.

Heat an oven to 415°F.

Spray both sides of the tortillas with the cooking spray and place on the baking sheet. Place the sheet in the oven for 4 minutes, then flip the tortillas and cook for another 5 minutes. They should be golden and crispy.

Heat the frying pan over medium high heat and add the beef, using the spoon to break it up and stir it around. Add the garlic powder, taco seasoning, and a generous pinch of salt. Cook until the beef develops a deep brown colour.

Once the beef has developed the right colour, add the onions and continue cooking until the onions have softened, about 5 or six minutes.

Spoon the beef mixture onto the cooked tortillas.

Arrange the tostadas on a plate, and top with the toppings of your choice.