Heat your oven 180°C/Fan 160°C/Gas 4. Peel and finely chop the red onion into ½cm dice. Dice the tomatoes and cucumber to match. Pop them all into a large bowl.
Halve the chilli, scoop out the seeds and white pith, and finely chop the chilli. Roughly chop the parsley (leaves and stalks). Add them all to the bowl and give everything a good stir to mix.
Finely grate in the zest from half the lemon. Squeeze the juice from that half into a separate bowl. Peel and crush or grate the garlic. Add to the lemon juice with 2 tbsp olive oil and a pinch of salt and pepper. Whisk well to make a dressing. Add to the veg and turn to coat. Leave the salad to rest and absorb the flavours for 5-10 mins.
Tear 2 of the tortillas into small, bite-size pieces. Spread them out on a baking tray. Bake in the oven for 5-10 mins till golden and crisp. While the flatbreads bake, crumble half the pack of feta.
Add the crisp flatbreads to the salad and toss. Heap up on 2 plates, scatter over the feta and serve straight away (the crisp flatbreads will soften as they sit in the salad, so it's best eaten immediately).