Put rinsed lentils in a medium pot and pour in purified water or vegetable stock until they are covered by 2-3 inches of liquid. Cover with a lid, bring to a boil, and then turn down to a simmer. Cook until the lentils are completely soft, yet still holding their shape. I often let them cook as long as 1.5 to 2 hours on low heat, just to really get them soft (and digestible!). Once they’re done, drain the liquid from the lentils.
While the lentils are cooking, place sliced onions, 2 tbsp. olive oil, and 2 tbsp. balsamic in a large frying pan. Add a few pinches of salt. Sauté on medium heat until they are deep brown and have reduced significantly. Stir as they cook, until some of the onions may even become crisp and caramelized. Approximately 20-25 minutes depending on heat. Remove from heat. Pull about a few tablespoons of the onions out of the pan to top your dish, or individual servings.
Empty the drained lentils into the frying pan with the onions and mix, adding a tablespoon each of olive oil and balsamic vinegar. Add salt, starting with ½ teaspoon. Incorporate and check for taste. Add pinches more of salt, olive oil, and balsamic, until the umami is popping and it makes you do a yummy lentil dance.
Mix all ingredients for the lemon fennel yogurt in a small serving bowl. Taste for salt levels and adjust accordingly. Stir in a drizzle of olive oil and top with a few extra fennel fronds, because it looks real purty. (Yes, that’s a legit reason.)
Serve the lentils family style on a platter, topped with the yogurt and the caramelized onions you set aside, or individually, topped the same way. Enjoy!