Using the same pot, add olive oil and onions. Sauté on a medium heat until the onions are golden brown and caramelized, about 8-10 minutes.
Add the garlic and seasonings and sauté for a minute. Add the drained red lentils, warm beef stock and potatoes. Simmer on a low heat for about 10-15 minutes. Once the potatoes are almost done, you'll add the broccoli. Simmer on a low heat until the potatoes tender. Note: feel free to add any additional stock if you'd like, a soups consistency depends on personal preference.
Add the meatballs and allow to simmer for another 5 minutes or so. Note: if your meatballs fully cooked in step #1 then there's no need to continue simmering. The residual heat will warm them up, ensuring you enjoy warm meatballs that aren't overcooked.
Finish off with cream, salt to taste and all that's left is for you to dish up so, enjoy!