Cut the onion in thin slices, take the ends of the haricots verts and cut the cherry tomatoes in half.
Let the onion marinate in some salt and the vinegar. This vinegar will be used later as well for the salad dressing.
Take the leaves from the little gem or romaine lettuce and wash quickly under cold water.
Layer the lettuce in a bowl, and tomatoes, basil leaves & feta.
Cook the egg to your preferred cooking point. Easiest thing is to add the haricot verts the last 4 minutes of the cooking time.
In the meanwhile, you can make the dressing. Place the marinated onion on the salad and add the walnut oil to the vinegar. Whisk with some salt & pepper.
When the haricot verts and egg are cooked, drain them under cold water. Peel the egg and cut in 4 pieces. Add the haricot verts to the dressing, and mix through.
Add the egg and haricot verts to the salad, and pour over some dressing. Enjoy!