First, PRE-BAKE THE POTATOES. Start this AT LEAST 1 HOUR BEFORE COOK CREW.
If you do not know how to bake a potato, wash each of them then lightly dry and individually wrap in foil. Stab at least 8 times into the potato with a fork through the foil and then bake for at least 1 hour at 400°F or until you can easily pierce with a fork. Let cool.

Then once the potatoes have been baked, slice them in half and scoop out the inside of the potato, leaving ~1/4" layer of potato still on the skins; the shell should remain intact since you'll be stuffing them again later. Scoop gently but you don't need to be a perfectionist. Set the skins aside for now.

Mash the potato insides with the vegetable broth in a bowl. Preheat the oven to 400°F again. Heat oil in a frying pan over medium-high heat (preferably peanut but olive or vegetable oil will do--they just have a lower burn temperature so be careful). Crush the coriander seeds on a cutting board, then add them along with the mustard seeds to the pan; the mustard seeds should pop within a few minutes; if they don't turn up the heat. Put a lid over the pan so the seeds can pop for a minute or two without you getting splattered.

Add the diced onion and carrots and saute for 7-10 minutes or until the onions begin to brown. Add the minced/food-processed garlic and ginger and continue to saute. Add the cumin, turmeric, and salt along with a little water and stir well. Finally add the potato mash and peas. Add water if it looks too dry. Cook until the potatoes and peas are heated through. Add lemon juice to taste.

Fill the potato skins with this mixture and then bake again for ~20 minutes in your now-ready oven at 400°F.