Grind the coriander seeds and peppercorns in a spice grinder or mortar and pestle.
In a large bowl, mix together the three flours. Add the ground spices and the next several ingredients up to and including the asafoetida. Mix well. Then add the yogurt and lime and mix with your hands as if you were making a dough. Taste and adjust flavors, adding more flour if the mix is too soft. Set aside.
Get the steamer ready. Lightly oil the steamer tray (I prefer perforated ones). Shape the dumplings into 4"- to 5"-long cylinders and place in the trays spaced well apart. Steam for 12-15 minutes until cooked through and firm to the touch.
While the dumplings steam, heat the oil in a small skillet over medium high. Add the mustard and sesame seeds and fry, shaking the pan frequently, until the mustard seeds begin to pop. Turn off heat and set aside.
Plate the steamed dumplings and pour the tempering oil over them. Alternatively (and this works quite well when reheating), fry the steamed dumplings in a tablespoon or so of oil with the mustard and sesame seeds until golden brown.
Garnish with cilantro and serve with green chutney.
Recipe by Oishii Rasoi at https://www.oishiirasoi.com/gujarati-steamed-vegetable-dumplings-muthia/