Dressing - Put all the ingredients EXCEPT the water in a jug just large enough to fit the head of a stick blender. Blitz until smooth. Add water 1 tsp at a time until it's a thick drizzle-able consistency (don't dilute flavour too much).
Step 2
Salad - Place all the salad ingredients EXCEPT the feta and tuna in a large bowl. Pour over the dressing, toss. Crumble feta in, toss (it will smear - we like!). Add the tuna and gently toss, trying to keep some chunks rather than it all crumbling into tiny pieces.
Step 3
Serve in bowls with spoons for digging in! Tuck warm pita pockets on the side, or use the tuna salad to stuff inside the pita (it's sooooo good!).