Combine everything except the pork in a medium bowl and mix until it is a smooth paste. Add the pork to the bowl and cover the steaks with the paste. Leave to marinate for 10 minutes.
Heat a skillet over medium heat. Lightly spray each of the pork steaks and add to the pan rather than the pan to avoid smoking out your kitchen. Cook for 3-5 minutes per side, adding the onion and remaining marinade halfway through (i.e. when you flip them).
Once cooked through, remove the pork steaks from the pan and chop into 1/4 inch cubes. Return the meat to the pan and stir until the onions are evenly dispersed.
For the salsa and assembly:
Place the avocado, peach, salt and onion in a small bowl, then juice the lime over the top. Stir gently to mix.
Heat a large pan over medium heat. Lightly warm the tortillas by placing them in the pan for 15 seconds per side.
To serve: spoon a little of the pork onto each tortilla, and top with peach salsa.