Heat mustard oil in a large skillet over medium-high heat. Once the oil is hot, add the cumin seeds and allow them to sizzle for a few seconds until fragrant. Stir in the ginger-garlic paste and sauté for about a minute until aromatic.
Add the finely diced onions to the pan and cook, stirring occasionally, for about 4–5 minutes or until softened and lightly golden. Toss in the chopped tomato and continue cooking for another 2 minutes until it begins to break down.
Sprinkle in the garam masala, coriander powder, turmeric powder, red chili powder, and a pinch of salt. Stir constantly to ensure the spices bloom evenly and coat the onion-tomato mixture thoroughly.
Add the diced potatoes, chopped carrots, and bell pepper. Mix well so that the vegetables are enveloped in the spiced masala base. Pour in a splash of water or vegetable broth if the mixture appears too dry.
Cover and simmer over low heat for about 10–12 minutes, or until the vegetables are tender and cooked through. Add the green peas during the final few minutes of cooking and allow them to soften.
Once the vegetables are tender, stir in the lime juice and chopped coriander leaves. Mix everything well to combine the flavors.
Serve the hot curry with freshly steamed basmati rice or warm chapati for a satisfying and wholesome meal.