From Een nieuw zuidnederlands kookboek uit de vijftiende eeuw (1560)
Totten soppen van poereen
Neemet puereije van erweijten als zij op haer breken zijn, ende laet dat zeer zieden te voren alleen, ende dan doet men daerin onioene, ende olije te samen gebert, ende daerna nemet comijn, sofferaen, ende vrijft dat ontwee, ende slaet duer een stamijn metter pureijen, ende laet dat naesieden.
Dutch Pea Soup
For soup of cooking liquid of peas.
Take liquid of peas when they start to break, and let that boil well with nothing added. Then one adds onions and oil, fried together. Then take cumin and saffron and grind this. Strain through a sieve with the liquid, and let is simmer.
Translation from https://coquinaria.nl/en/medieval-pea-soup/
Recipe
1/2 lb. dried peas, soaked as per the package instructions
1 large onion
generous pinch saffron
1/2 tsp. cumin seeds
1/2 tsp. salt
sugar to taste (optional)
Simmer the peas in water until they are done. Drain the peas, reserving the liquid. Puree, using reserved liquid, until desired consistency. Sweat the onions in oil until tender. Grind the cumin and saffron together.
Return the pea puree to your pot, then add the onions and spices. Heat gently for another 10 minutes to release the saffron flavor. Serve forth.
Based on my experience with the Thick Pea Soup, if you use fresh or frozen peas, you won’t need to add any sugar.