Heat oil in a pan and add cumin seeds. Let them sizzle for 30 seconds.
Add onions and sauté until golden brown. Stir in garlic and ginger, cooking for 1-2 minutes.
Add turmeric, coriander powder, and red chili powder. Cook for 1 minute.
Add tomatoes and cook until they form a thick sauce, about 5-7 minutes.
Add diced potatoes and stir to coat. Pour in 1 cup of water, cover, and simmer for 15-20 minutes until potatoes are tender.
Add green peas and cook for another 5 minutes.
Sprinkle garam masala and garnish with cilantro. Serve hot with rice or bread.