Start by rinsing the beluga lentils under cold water. This simple step helps remove any impurities. In a medium saucepan, combine the rinsed lentils with three cups of water and a pinch of salt.

Bring to a boil, then reduce the heat to low and cover. Let the lentils simmer for about 20-25 minutes, or until tender but still firm. Avoid overcooking, as lentils can become mushy, and we want them to hold their shape.

While the lentils are cooking, heat the olive oil in a medium skillet over medium heat. Add the thinly sliced onion and a pinch of salt. Sauté for about 8-10 minutes, or until the onion turns golden brown and soft. This step intensifies the sweetness of the onions, adding depth to the dish.

Add the fresh spinach leaves to the skillet with onions. Stir them in and cook until just wilted, about 3-4 minutes. The spinach will reduce significantly in volume but will retain a vibrant color. Remove from heat and set aside.

In a mixing bowl, combine the Greek yogurt, freshly squeezed lemon juice, chopped dill, and kosher salt. Mix until well incorporated. If the sauce seems too thick, feel free to add a splash of water to reach your desired consistency. This sauce is refreshing and offers a delightful zing.

Once the lentils are cooked, drain any excess water and add them to the skillet with spinach and onions. Stir to combine all ingredients and let them warm through. Taste and adjust seasoning with additional salt and pepper as needed.