To begin we'll make the dressing. The reason we are starting with the dressing is that it will sort of quick-pickle the red onion so it is not so sharp. Whisk together the Olive Oil, Lemon Juice, and the Salt, then add the thinly sliced red onion to it. It will soak while you prepare the other ingredients.
In a large bowl add the chickpeas, tomato, cucumber, spring onion, basil and mint.
In a pot of boiling water, drop in the rock samphire for 2 minutes, then remove and place in an ice water bath.
Add the oregano and rock samphire and mix well. Toss in the dressing with the red onion and mix again. Drop on some cubes of feta cheese and serve the chickpea salad in a large sharing bowl, or individual portions.