I was actually a bit skeptical at whether this red lentil dal would be flavorful enough given how few spices were in this recipe, compared to many other Indian recipes I’ve tried - but it was perfect. I did modify the recipe slightly in a few ways based on what I had on hand and knowing I wanted it to be thicker (vs soupier) - feel free to tweak based on your own pantry and tastes. I didn't have asparagus, so I didn't include.
Add the lentils and the water to a medium saucepan and bring to a boil. Skim off any foam that develops and stir in 1/8 tsp of the turmeric until incorporated. Lower the heat and simmer the lentils over low heat until softened, which could take as little as 15 minutes (start checking at that time).
While the lentils are cooking, mince the garlic and slice the shallot, and get your spices together. Heat the oil in a large skillet over medium heat, until almost shimmering, then add the mustard seeds. Be sure to shake the pan a bit so the heat is evenly distributed, and listen for them to start popping, about 1 minute. Add the fennel seeds, ground coriander, the remaining 1/8 tsp turmeric, jalapeño, garlic and onion to the pan, stirring to coat all the spices in the oil - and cook over medium-low heat until the shallot has softened, about 8 minutes.
When the lentils are done cooking and the garlic/shallot/spice mixture in the skillet is soft and fragrant, add the lentils to the skillet, add the tamarind paste (or lemon juice), and stir everything together to combine well. I cranked the heat up in the skillet for another minute or two to evaporate off just a bit more moisture and let the flavors really combine.
Season with salt to taste, and serve over rice or with naan.
Pro tip: Do not, under any circumstances, cut up your pepper and then touch your eyeball. Does this seem obvious? Just thought I'd remind you out of an abundance of caution...that you may learn from my error. Clearly I didn't wash my hands well enough; on the flip side, I did learn that pouring copious amounts of milk in your eye and soaking a paper towel in milk and holding it there like a compress helps. The more you know!