Gather all your ingredients and chop the onion, garlic, and ginger so everything is ready to go.
Heat oil in a large heavy-bottomed pot over medium heat until it shimmers and begins to gently smoke.
Add the chopped onion and cook, stirring often, until it turns translucent and starts to develop a golden hue, about 8 minutes. The kitchen will fill with a sweet, aromatic smell.
Stir in the minced garlic and ginger, cooking until fragrant, about 1 minute. Be careful not to burn the garlic—if it starts to darken, lower the heat slightly.
Add the cumin seeds, turmeric, and coriander powder. Toast the spices, stirring constantly, until they release a fragrant aroma, about 30 seconds to 1 minute.
Stir in the rinsed red lentils, coating them with the spices and aromatics. Pour in the vegetable broth or water, then bring the mixture to a boil.
Reduce the heat to low and let the curry simmer, uncovered or partially covered, for 20-25 minutes, stirring occasionally. The lentils will soften and start to break down, creating a velvety sauce.
Stir in the coconut milk, squeeze in fresh lemon juice, and season with salt. Let it cook for another 5 minutes, allowing the flavors to meld and the curry to thicken slightly.
Taste the curry and adjust seasoning as needed—add more salt or lemon for brightness. Garnish with chopped cilantro for a fresh herbal touch.
Turn off the heat and let the curry rest for a few minutes. Serve hot, accompanied by rice or bread, and enjoy the rich, velvety texture and warm flavors.