Soak masoor dal in 4 cups water; swish with your hands to clean. Drain; repeat twice.
Combine onion and 1/2 cup water in a saucepan over medium-low heat; simmer until water is absorbed, 5 to 7 minutes. Add oil and garlic; cook, stirring occasionally, for 3 minutes. Add bebere powder; cook and stir for 3 minutes more.
Mix tomato sauce and 1/2 cup water into onion-spice mixture; bring to a boil. Add masoor dal and carrots; reduce heat to low. Cook, stirring occasionally and adding water as needed to maintain a soupy consistency, until carrots are just tender, about 5 minutes. Add zucchini; cook and stir until masoor dal is tender, about 5 minutes. Add salt.