Wash and spin the lamb‘s lettuce dry in a salad spinner.
Peel the cucumber and cut in half lengthwise, then slice.
Cut the avocado in half lengthwise, twist the two halves apart, remove the pit, and scoop out the flesh with a spoon. Cut in into slices.
Toast the pumpkin or sunflower seeds (or use both types of seeds) in a dry pan until fragrant and slightly golden, transfer them into a plate (be careful, they can easily burn).
Make the honey mustard vinaigrette:
Pour the ingredients for the sauce into a small jar, close the lid and shake until well combined. Alternatively, mix the vinaigrette ingredients in a food processor at low speed.
Assemble the salad:
Toss the lettuce with all the vegetables and seeds, pour over the sauce. Season with salt and pepper to taste. Crumble the feta cheese on top.
Serve immediately because lamb‘s lettuce fades very quickly!