Divide a peach in half and cut one half into chunky slices. Place it in a shallow serving dish. Place the other half in the fridge to use for something else.
Cut the Persian cucumbers into 1/4 inch slices on the diagonal, and place in the dish with the peaches.
Cut the scallions on the diagonal in 1/4 inch slices, and add them to the bowl.
Scatter whole or torn mint and basil leaves over the top of the salad.
Do the same with the sliced Serrano peppers.
Crumble the feta into big chunks on top of that.
Zest the lemon over the top of the salad, and season with salt, pepper, and za'atar. Set aside.
Place the lemon and lime juices, Ume extract syrup, extra virgin olive oil, dark brown sugar, and fish sauce into a small bowl and whisk thoroughly. Serve dressing along side of the salad so people can help themselves.