Step 1
Start the stew: Place the lappeh or chana dal in a bowl and cover with 3 cups cold water.
Step 2
While the lappeh soaks, in a kettle or a saucepan, bring 8 cups of water to a boil and keep at a lively simmer. In a large (5-quart) Dutch oven or similar pot, heat 1/4 cup of oil over medium. Add the onion, give a quick stir to coat, and cook without stirring until the onion starts to turn golden at the edges and decreases in volume, 6 to 8 minutes. Begin to stir frequently and keep cooking until mostly golden throughout, 4 to 6 minutes more.
Step 3
Season the onion with a little salt, add the turmeric and stir until fragrant, about 30 seconds. Add the meat, give a quick stir to coat in the onion mixture, spread evenly over the bottom of the pot and don’t touch for 1 minute. Then cook, stirring frequently, until the meat is no longer pink, 2 to 3 minutes. Season with 2 teaspoons salt and 1/2 teaspoon pepper.
Step 4
Adjust heat to medium-low and add the tomato paste. Cook, stirring frequently, until the tomato paste releases its color into the oil, 2 to 3 minutes. (This step is very important for the final hue of the stew.) Add the cinnamon stick, give a quick stir and pour in enough boiling water to cover the meat. (You’ll use 2 1/2 to 3 cups water; reserve the rest for later.) Bring to a boil, stir, cover, adjust heat to low and gently simmer, stirring once in a while, for 1 hour, until the meat is tender.
Step 5
While the meat simmers, prepare the saffron water: Using a mortar and pestle (or a spice grinder), grind the saffron to a fine powder (you will have a scant 1/4 teaspoon). If needed, add a small pinch of sugar to the threads to help with grinding. Add 2 tablespoons of the boiled water, gently stir, cover and let steep until ready to use. (If using a spice grinder, transfer the powdered saffron to a small glass to steep.)
Step 6
Soak the limoo Ammani: Firmly hold one limoo Ammani at a time on a board and, with a fork or the tip of a paring knife, carefully puncture it a couple of times. Place in a small bowl, cover with boiled water and place another small bowl on top to submerge the limes. Let soak for 15 minutes to remove their bitterness. Drain and set aside until ready to use.
Step 7
Parcook the lappeh: In a medium saucepan, heat the remaining 1 tablespoon of oil over medium. Drain the lappeh, transfer to the saucepan and cook, stirring constantly, for 3 minutes (avoid overcooking, which would toughen the peas). Cover with 4 cups of the boiled water and add 1 teaspoon salt. Bring to a boil over high, adjust to a simmer, partially cover and cook, stirring occasionally and skimming off any foam, until the peas are al dente, 10 to 15 minutes. Drain, rinse with cold water and set aside.
Step 8
When the meat has simmered for 1 hour, add the parcooked lappeh, drained limoo Ammani and 1 tablespoon of the saffron water to the stew, adjust heat to medium and bring back to a rapid simmer. Cover, adjust heat to low and simmer for 30 to 40 minutes, occasionally using the back of a wooden spoon to gently squeeze the limoo Ammani against the side of the pot, until the stew comes to life: The lappeh are tender but maintain their shape, the oils have risen to the surface and the flavors have come together. As the stew simmers, taste for salt and adjust as needed.
Step 9
Remove the cinnamon stick, stir in the remaining saffron water and add lime juice to taste, 1 tablespoon at a time. Cook for 10 to 15 minutes more, until the consistency of the stew is not too thick and not too runny. (You should be able to spoon the sauce over rice.) Adjust as needed: Add just-boiled water to thin out a little, or simmer uncovered to thicken. (The stew will also thicken as it sits.)
Step 10
While the stew simmers, prepare the fried potatoes (if using store-bought potato sticks, skip this step) so you can serve them hot when the stew is ready (or keep warm in a 250-degree oven). Drain the potatoes and thoroughly pat dry with a clean kitchen or paper towel. Place a wire rack over a sheet pan (or line sheet pan with paper towels). In a large (12-inch), high-sided pan, heat the oil over medium-high until hot, about 2 minutes. Add the potatoes and give a quick stir with a slotted spoon. Fry without stirring (so they don’t break) for 4 minutes. Sprinkle the turmeric (if using) into the pot and continue to cook, stirring frequently, until the potatoes are golden and beginning to crisp, 3 to 5 minutes more. Transfer to the sheet pan and sprinkle with a little salt.
Step 11
Transfer the stew to a serving dish, scatter the fried potatoes on top and serve with rice.