Throw the potatoes in a large pot, cover with room temperature water, and season with salt. Set on a high flame and bring to a boil. Reduce to a simmer and cook until a fork inserted into the potatoes draws out without resistance, 15 to 20 minutes. Drain and set aside to cool. Once they're cool enough to handle, cut each potato into bite-size pieces.
In a large skillet or wok, warm the oil until it's shimmering but not smoking. Add the fennel seeds; they should sizzle upon contact with the oil. Immediately add the potatoes, coriander, turmeric, thyme, salt, and pepper. Stir-fry until the potatoes get crispy and golden brown on the outside. Finish with the fresh cilantro and lime juice and serve.