This is a recipe from Galen's, On the Power of Foods. Galen was the most famous Roman doctor and served emperors Marcus Aurelius and Commodus.
Galen says this dish is good for both the healthy and sick.
You first boil 100g of green lentils in 750 ml of spring water. Boil the lentils for 20 min, then add 2 tbls of olive oil and 1 tbls of garum. Then add two handfuls of beet leaves (the leaves were often used by the Romans over the root). Boil for 10 more minutes and serve.