Step 1

If you own a stovetop-safe slow cooker insert: Heat the olive oil in the insert over medium heat on the stove. Add the onion and celery and saute until tender, 5 to 7 minutes, before transferring to the slow cooker and continuing with the instructions below.

Step 2

If you do not own a slow cooker with a stovetop-safe insert (or wish to skip step one): Place the insert on the slow-cooker base (this recipe will fit a 4-quart capacity slow cooker). Add the olive oil, onion, celery, carrot, zucchini, potatoes, split red lentils, chopped tomatoes, parmigiano rind, bay leaves, thyme, chicken stock, kosher salt, and black pepper. Stir together. Cook on high heat for 4-6 hours, or until the red lentils are tender (or alternatively, cook on low heat for 8-10 hours).

Step 3

In the last hour of cook time (or 2 hours, if you are cooking over low heat), add the thinly sliced cabbage. Remove and discard the dried bay leaves and any tough thyme sprigs. Adjust the seasoning to taste salt and pepper – you will most likely need to be liberal on the salt for this soup!

Step 4

Serve the soup and top each serving with a drizzle of extra virgin olive oil, a sprinkling of freshly chopped parsley, and freshly grated parmigiano-reggiano.