Prep
- Heat oil in a medium pot over medium-high heat. Add onion and cook, stirring occasionally, until softened and lightly browned around the edges, 5–7 minutes.
- Add ginger and garlic and cook, stirring often, just to take the edge off garlic, about 30 seconds. Add ⅓ cup water and simmer, stirring occasionally, until water evaporates about 1 minute.
- Add the lentils, coriander, turmeric, cardamom, and red pepper flakes and cook, stirring, until fragrant, about 30 seconds.
- Add 4 cups water to the lentil and spice mixture and bring to a boil. Reduce heat to medium-low and simmer, stirring occasionally, until the lentils are very tender and most of the liquid is absorbed, 20-25 minutes; season with salt and black pepper to taste.
- Cover dal with a lid and keep warm over low heat while you make the toppings.
- Finely grate the zest from lime into a small bowl. Cut lime in half and squeeze juice into a bowl (approximately 2 tablespoons). Add red onion, sugar, and a large pinch of salt and toss, squeezing onion with your hands to help it soften quickly.
- Mix cashew milk yogurt and 2 tablespoons water in a small bowl; season with salt.
- Serve dal over rice and top with the cashew milk yogurt sauce and pickled onions.
