Heat the olive oil in a large pot over medium heat until it shimmers and starts to smell fragrant.
Add the diced onion and cook, stirring occasionally, until translucent and lightly golden, about 5-7 minutes. The kitchen should fill with a sweet aroma as the onions soften.
Stir in the minced garlic and grated ginger, cooking for about 1 minute until fragrant and slightly bubbly.
Add the toasted cumin seeds (crushed slightly to release aroma) and turmeric powder. Stir for 30 seconds until the spices release their warm, earthy fragrance.
Pour in the vegetable broth and bring the mixture to a gentle boil, stirring to combine the spices evenly.
Add the rinsed red lentils to the boiling broth, stirring once to prevent sticking. Reduce the heat to low and let simmer, uncovered, for about 20 minutes, stirring occasionally, until the lentils are tender and begin to break down, thickening the sauce.
Stir in the coconut milk, allowing the curry to simmer gently for another 5 minutes. The sauce should become velvety and rich in appearance.
Taste and adjust the seasoning with salt and pepper. Squeeze in fresh lemon juice to brighten the flavors and stir to combine.
Remove from heat and sprinkle with chopped cilantro for a fresh, herbal contrast. Let sit for a few minutes to allow flavors to meld.
Scoop the warm, silky curry into bowls and serve over rice or with naan bread for a complete meal. Enjoy the comforting aroma and flavorful bite.