Start by peeling and cubing the potatoes into roughly 1-inch pieces, then set them aside. Dice the onion, mince the garlic, and grate the ginger. Prepare the broccoli florets, cutting them into small, bite-sized pieces.
Heat the oil in a large heavy-bottomed pot over medium heat until it shimmers and starts to gently ripple. Add the diced onions and sauté for about 5 minutes, stirring occasionally, until they become soft and translucent with a sweet aroma.
Stir in the minced garlic and grated ginger; cook for about 30 seconds until fragrant, filling the kitchen with a warm, spicy aroma. Be careful not to let the garlic burn.
Add the cumin seeds or ground cumin and turmeric powder to the pot. Toast the spices for about 1 minute, stirring constantly, until they release their aroma and turn a slightly darker shade.
Pour in the water and coconut milk, then add the cubed potatoes. Stir everything together, making sure the potatoes are coated with the spice mixture. Bring the mixture to a gentle simmer, then cover partially and cook for about 15 minutes, stirring occasionally, until the potatoes are soft and starting to break down into a silky sauce.
Uncover the pot and add the broccoli florets. Stir to combine, then cook uncovered for another 5 minutes, until the broccoli is bright green and just tender with a slight crunch.
Taste the curry and season with salt and pepper as needed. If you like it spicy, stir in chili powder or cayenne at this stage. Once seasoned, squeeze a little lemon or lime juice over the curry to brighten the flavors. Stir well to incorporate.
Remove the pot from heat and let the curry rest for a couple of minutes. This helps the flavors meld and the sauce to thicken slightly. Serve hot, spooned over rice or with crusty bread, and enjoy the cozy, fragrant meal.
