Cut the potatoes into bite-sized pieces and put them in a bowl with the peas and spring onions.
Combine the ingredients for the vinaigrette - olive oil, lemon juice, lemon zest, mayonnaise, honey and Dijon mustard. Season with salt and freshly ground pepper and shake or whisk the vinaigrette together.
Pour the vinaigrette over the salad and toss well.
Tear the lettuce leaves roughly and add them to the salad along with the feta, then toss the salad quickly.
Taste and add more salt and freshly ground pepper if needed, and serve the salad straight away - top with a little finely grated lemon zest if you like.The salad is best freshly made, while the lettuce is still crisp. If you need to make it ahead, I recommend waiting to add the lettuce until just before serving - and ideally holding back the vinaigrette as well.If the potato salad has already been mixed, I recommend taking it out of the fridge 20-30 minutes before serving.