"This is an authentic, vegetarian, simple, and colorful main dish served with fluffy basmati rice or chapatis. I'm from India and I completely adore Indian cooking; I hope you like this recipe. A word of caution: it could be a little too hot for some folks...feel free to reduce or even skip the hot ingredients! Enjoy!"
Heat vegetable oil in a skillet over low heat. Stir mustard seed into hot oil; cook and stir until seeds start to crackle, about 30 seconds. Stir garlic, green chile pepper, curry leaves, cumin seed, and asafoetida powder into mustard seeds; cook and stir until the garlic is fragrant and beginning to turn golden, 3 to 5 minutes.
Stir tomatoes into garlic mixture, increase heat to medium, and cook, stirring frequently, until the tomatoes are softened, about 10 minutes. Add water, cumin, cayenne pepper, coriander, and turmeric to tomato mixture; stir.
Mix potato, bell pepper, lemon juice, and salt into tomato mixture; bring to a boil, reduce heat to medium-low, cover the skillet with a lid, and simmer until potatoes and peppers are tender, 15 to 20 minutes. Garnish with cilantro leaves.