Mujaddara with Spiced Yogurt

This vegetarian dish is super easy and cheap to make, but it's also really delicious.  I do suggest splurging to get the French lentils the recipe calls for - overall, the dish is still very inexpensive, and they're so much tastier than regular brown lentils, at least in my opinion!  This is one of those dishes that's nothing special right when you make it, but once the flavors have the chance to combine it becomes wonderful.  So, make sure to prepare it ahead so it has time to rest in the fridge for at least a few hours before you serve it.  Since mujaddara only gets better over time, it's a great candidate for making a big portion over the weekend and packing for lunch.  It's especially good with the spiced yogurt on the side.  The flavor of the yogurt is somewhat strong on its own, but don't be scared - it's very yummy mixed into the rice and lentils.

Mujaddara with Spiced Yogurt (adapted from food52, original recipe here)
Serves 2-3

1/4 cup plus 2 T lentils de Puy (French lentils)
Salt
1 T butter
1-1/2 T olive oil
1 large onion, peeled and thinly sliced
1-1/2 to 2 cups cooked white rice (depending on the balance you like; 1/2 cup uncooked rice will make the correct amount if you don't have any ready)

For the yogurt:
1/2 cup nonfat Greek yogurt
1/2 tsp cinnamon
1/2 tsp ground cumin
1/2 tsp ground coriander
1/2 tsp smoked paprika
Juice and zest of 1/2 lemon
1/2 tsp salt

1. Put the lentils and 2 cups water in a pot along with about 1/4 tsp salt.  Bring to a boil, and then lower to a simmer and cook about 20 minutes, until the lentils are tender but not mushy.
2. Melt the butter and olive oil in a non-stick skillet or large nonstick Dutch oven over medium heat.  Add the onions and stir frequently until they soften and release their liquid.  Sprinkle with salt, and then continue cooking for about 10 minutes, until the onions are very browned and softened.  When the onions are nicely browned, turn the heat up to high, adding a bit more oil if needed, and cook, stirring infrequently, until the bottom layer of onions becomes a bit crispy.
3. Stir together the lentils, onions, and rice, adjusting the amount of rice you use for the balance of rice-to-lentils that you prefer.  Let cool slightly, then cover and chill for at least a few hours.
4. Reheat the mujaddara in a low oven or the microwave before serving.
5. To serve, stir all the yogurt ingredients together.  Taste and add more yogurt or spices as needed, and serve alongside the mujaddara.