Preheat the oven to 180°C (350°F) and line a baking tray with parchment paper.
Add the olive oil, grated garlic, and salt directly onto the parchment paper and mix briefly.
Tear the pita bread into bite-sized pieces over the tray and mix well with your hands so all pieces are evenly coated.
Spread the pita in a single layer and bake for 10–15 minutes, stirring once halfway through, until golden and crispy. Keep an eye on it, as some pieces brown faster. Set aside to cool.
While the pita bakes, prepare the vegetables. Cut them into chunky, bite-sized pieces and add to a large bowl. Roughly chop the herbs and add them as well.
In a small bowl, whisk together the lemon zest, lemon juice, olive oil, salt, and black pepper.
Just before serving, add the dressing to the vegetables and toss gently. Add the cooled pita croutons, toss again, then finish with feta and a sprinkle of sumac.