Use a glass jar that you can put the lid on later. Put the Ketchup and brown sugar in the jar, mix and heat in the microwave for 1 minute at medium heat. Then put the olive oil, vinegar and salt and shake vigorously with the lid on. Save for later.
Place in the plate the mixed greens, the cherry tomatoes cut in half, bite size slices of the acorn-fed Ibérico Ham, thin slices of foie-gras and the walnuts.
Just before serving, shake again the salad dressing and pour it over the salad. Decorate with Maldon salt if desired.