I never met a lentil I didn’t love. This is a lovely way to eat them, and very easy to make. It was a great standby for me during chemo. The trick is not... to overcook the lentils before transferring them to the skillet. They should be soft, but not mushy so they don’t fall apart when you add the stock.
Put the lentils, onions, carrots, celery, and bay leaves into a 3-quart saucepan. Pour enough cold water over to cover by 2-inches. Bring to a boil over high heat. Reduce the heat to medium and bring to a gentle boil. Add ½ teaspoon salt.
Cook until the lentils are just tender, 20 to 25 minutes. Drain the lentils, discard the bay leaves, and transfer to a large skillet.
Pour in the chicken stock and olive oil. Stir to mix. Taste for salt and season lightly with salt and pepper. Bring to a gentle boil and cook until the liquid has reduced, about 3 minutes.
Scatter the spinach over the lentils and toss just until the spinach is wilted, about 1 minute. Taste and adjust seasoning as necessary. Serve immediately.
Check the lentils for doneness after about 15 minutes. As with all dried beans, the older they are, the longer they will take to cook. I have found cooking times often assume older goods.
Be sure to buy the small rosy brown lentils to make this dish. The usual green varieties are too soft and will not hold up.