Whisk together the honey, lemon juice and walnut oil. Season to taste with salt, freshly ground black pepper and cayenne pepper. Set aside.
Separate the lettuce leaves, discarding any tough outer leaves. Wash and spin dry before placing in a large salad bowl. Rip any particularly large leaves.
Add the sliced spring onions, mint leaves, feta cheese and walnut kernels. Re-whisk the vinaigrette, pour on to the salad and gently mix. Serve immediately.