In a large Dutch oven or stock pot, heat the oil over medium heat.
Saute the onions until softened, around 4 minutes. Stir in the garlic and butternut squash, then continue to cook for a minute longer, until the garlic releases its flavor.
Add in your dried lentils and pour in the stock then bring the soup to a boil, then reduce to a gentle simmer.
Simmer, covered, for 20-25 minutes, or until the lentils are tender and the soup has thickened a bit.
Add the chopped kale, lemon zest, and lemon juice then stir to combine.
Taste test and add a pinch of sea salt if desired.
Serve warm with yogurt if desired and a pinch of chili flakes.
Enjoy!