Mujaddara with Spiced Yogurt

Name: Mujaddara with Spiced Yogurt
Ingredients: For the Mujaddara; 3/4 cup Puy lentils (aka French lentils, the tiny dark brown ones); 1 teaspoon salt, divided; 1 cup jasmine rice; 2 tablespoons butter; 3 tablespoons olive oil; 6 cups onions (about 3 medium onions), halved and thinly sliced; For the yogurt; 1/2 cup Greek yogurt; 1/2 teaspoon cinnamon; 1/2 teaspoon cumin (freshly ground, if possible); 1/2 teaspoon coriander (freshly ground); 1/2 teaspoon spicy paprika or aleppo pepper; 3 tablespoons chopped fresh mint; Juice and zest of half a lemon; 1/4 teaspoon salt