Heat the vegetable oil in a large pan over medium heat until it becomes hot.
Sauté the chopped onion until it turns golden brown.
Add the minced garlic and ginger paste, and cook for an additional minute until they release a fragrant aroma.
Add the coriander powder, cumin powder, turmeric powder, red chili powder, and salt into the pan, stirring well to combine with the onion and garlic mixture.
Place the chicken in the pan and cook until it becomes browned on all sides.
Add the diced potatoes to the pan, mixing them with the chicken and spices.
Pour water into the pan, stirring everything together. Reduce the heat to low, cover the pan, and allow it to simmer for approximately 20-25 minutes, or until the chicken and potatoes are fully cooked.
Check the thickness of the sauce and add more water if desired to achieve a saucy consistency.
Sprinkle garam masala over the dish and thoroughly mix.
Remove the pan from the heat and garnish with freshly chopped coriander leaves.
Serve the Chicken Aloo hot, accompanied by rice or naan bread.