Heat the oil in a deep skillet or medium saucepan over medium-high heat.
Add the onion and cook, stirring occasionally, until soft and translucent, about 3-5 minutes.
Stir in the garlic and ginger and cook for another minute until fragrant.
Season with salt and pepper.
Reduce the heat to medium-low.
Continue to cook, stirring occasionally, until the onion mixture is golden and very soft, about 20 minutes. This step builds a deep flavor base.
Increase the heat to medium-high and stir in the turmeric and curry powder.
Cook, stirring constantly, until the spices are fragrant and slightly darkened, about 5 minutes.
Add the chopped tomato, coconut, okra, zucchini, and washed lentils to the pot.
Pour in the vegetable stock and coconut milk.
Stir everything together and bring the soup to a boil.
Once boiling, reduce the heat to a medium-low simmer.
Let the soup bubble gently, stirring occasionally, until the lentils and vegetables are tender and breaking apart, about 30-40 minutes. If the soup becomes too thick, add a splash of water to maintain a brothy consistency.
Just before serving, stir in the fresh curry or basil leaves.
Taste the soup and adjust seasoning with more salt and pepper if needed.
Serve hot.