Prepare lentils by adding lentils and broth to a medium stockpot over high heat. Bring to a boil, cover, and reduce heat to low. Set aside for 20 minutes, or until lentils are tender and liquid is absorbed.

In the meantime, prepare vegetables by dicing sweet potato, slicing leeks into half-moons, roughly chopping kale, and mincing fresh sage.

Add oil, leeks, and sage to a medium saucepan over medium heat and cook until aromatic and leeks are softened and translucent.

Add sweet potatoes and kale and cook until sweet potatoes are tender, and kale is wilted, for 12-15 minutes, stirring occasionally. Add a splash of water and cover if vegetables begin to stick to the pan.

Toss vegetables and lentils together and enjoy warm.