Cook peas: Have ready a colander and an ice bath, and bring a medium pot of lightly salted water to a boil. Blanche peas for 30 seconds (if you like them with a real residual snap) to 1 minute (for a slightly more yielding pea) and drain them, then immediately shocking them in the ice water. Drain the peas again and pat them dry on a large towel.
Crush peas: Using a potato or egg-masher, muddler or meat pounder (be gentle!), lightly crush the peas. Aim for mixed textures, some left whole, most in halves and a few a little more broken up. Put them in a large bowl.
Make dressing: Whisk together tahini, yogurt, lemon juice, water, cumin, paprika and salt. You might be tempted, as I was, to swap the water with olive oil but don’t do it — it makes a horrible curdled mess you will be sad to have to toss.
Assemble: Mix peas with about 3 tablespoons of the dressing, to start, then add more to taste. Sprinkle with scallions. Heap pea mixture on toasted pita wedges.