Preheat the oven to 365F.

Heat the oil over medium-high heat in a wide, ovenproof pot with a lid.

Once the oil is hot, stir in the mustard and cumin seeds and cover the pot.

When the seeds start to pop after about 1 minute, remove the lid, reduce the heat to medium, and add the curry leaves. Fry for 1–2 minutes, stirring, until fragrant.

Add the cumin, coriander, turmeric, and chili powder (if using), and cook for 1 minute, stirring constantly.

Add the potatoes and salt, and mix well to coat the potatoes evenly with the spices. Cook for another 5 minutes, stirring occasionally, until the potatoes begin to brown.

Turn off the stove, cover the pot, and place it in the oven.

Bake for 20 minutes, or until the potatoes are tender. 

Remove the pot from the oven. Do not stir the potatoes. Instead, using oven mitts, first remove the lid then gently shake the pot from side to side to loosen the potatoes from the bottom so they don’t break.

Spoon potatoes into a serving bowl. Sprinkle with chopped cilantro, if using, and season with additional salt to taste if needed. Serve warm. 

Aloo bhaji can be stored in an airtight container in the refrigerator for 4 to 5 days.