Heat the olive oil in a large saucepan or Dutch oven over medium heat.
Add the chopped scallions and curry powder, and cook, stirring constantly, until wonderfully fragrant, about 30 seconds.
Stir in the rinsed lentils, drained tomatoes, and vegetable broth. Increase the heat and bring the mixture to a boil.
Once boiling, decrease the heat to low.
Season to taste with salt and pepper, cover, and let it simmer for 10 minutes.
While the soup simmers, thinly slice the zucchini.
After 10 minutes, add the zucchini slices to the pot.
Continue to simmer until the lentils are completely soft and have started to break down, about 10 more minutes. If the soup becomes too thick for your liking, stir in up to 1 cup (240 ml) of water to reach your desired consistency.
Taste and adjust seasoning if necessary before serving hot.
Stir in a few large handfuls of fresh spinach or kale during the last 5 minutes of cooking for an extra boost of greens and nutrients.
Adjust the spice level by using a hot curry powder or adding a pinch of red pepper flakes along with the scallions for an extra kick.