In a large pot, heat some of the oil and toast the lentils. Add the aromatic herbs and the onion cut into slices. Pour water until the lentils are covered, then cook over low heat for about 45 minutes. Season with salt and pepper.
Cook the polenta in boiling salted water, then pour it into a pan when it is still boiling, so as to obtain a thickness of 2-3 cm. Leave to cool and obtain patties by cupping the polenta into a cylindrical shape of 5-6 cm in diameter (or the size you wish.
Cook the salami
Crumble the salami paste and cook it in a well-heated pan. Use it to complete each cake, together with the lentils. Drizzle with the remaining raw oil and serve.