Very closely adapted from Chitra Agrawal. I focused on spring vegetables; Agrawal, for example, uses broccoli in hers. I recommend using whatever is seasonal to your location.
If you are curious about asafetida, you can read about it here. I highly encourage you to not be put off by its pungent smell (although I do recommend triple bagging it!) because when it hits hot oil the scent is completely transformed.
Using a wet-dry grinder (or something powerful like a Vita-Mix), add the whole spices (the first 4 ingredients) and grind them to a powder. If using roasted dal, add it too.
Add the ginger and fresh chile pepper. Once again process, this time to a coarse grind.
Add the coconut and cilantro, along with enough water to get the blades moving. Blend and then scrape. Add more water if needed and blend again. Repeat until you have a smooth paste.
Place the potatoes in a sauce pan with enough water to cover them by about 2 inches. Add a pinch of salt and bring to a boil. If you like your carrots soft, add them now, but I do not.
Simmer for 7-8 minutes, until the potatoes are starting to get tender (they will continue to cook in the curry). Add the carrots (if you like them crisp-tender) and asparagus. Boil until the asparagus is becoming bright green but not quite tender.
Drain the vegetables, but be sure to reserve the cooking water.
Using a heavy bottomed pot, heat it over medium heat. Add the oil with the mustard seeds. Cover the pot, but leave the lid ajar to allow steam to escape.
Let the mustard seeds pop; when they slow down, add the asafetida and let it cook for about 1 minute (and take the time to appreciate how wonderful it smells after cooking despite its pungent raw smell!).
Add the curry leaves and dried red chile pepper (if using)--stand back because the curry leaves will splatter and pop!
When the splattering subsides, which will be less than a minute, stir everything to evenly coat it with oil.
Add the onions with a pinch of salt. Let it cook, stirring occasionally, until caramelizing, about 10 minutes. Add the turmeric powder and mix it into the onions.
Add the prepared curry paste and stir it into the onions. Let it fry for a few minutes.
Add the parboiled vegetables and stir them into the paste. Then add the reserved vegetable cooking water until you like the consistency of the curry--we prefer ours a bit more saucy than dry.
Simmer until the vegetables are cooked to your liking. Stir in the peas and cook until heated through (I like to add peas last because I loathe overcooked peas).
Taste for salt. A squeeze of lime or lemon juice would not go amiss if you feel like the curry needs brightening. To me this will depend on what vegetables you have used--we did not need it with the asparagus.
Garnish with cilantro. Serve with Basmati rice or flatbread like chapatis.