Heat oil in a large high-sided skillet over medium. Add onions and 1 teaspoon salt; cook, stirring occasionally, until onions are softened and light golden, about 20 minutes. Add berbere, garlic, and ginger; cook, stirring often, until fragrant and toasted, about 8 minutes, adding up to ¼ cup water, 1 tablespoon at a time, as needed to prevent onions and spices from sticking to bottom of skillet.
Add lentils and remaining 1 teaspoon salt; cook, stirring constantly, until lentils are coated in spice mixture, about 1 minute. Add 4 ½ cups water, and bring to a boil over medium-high. Cover; reduce heat to medium-low, and simmer until lentils are tender, about 25 minutes.
Stir mekelesha spice blend into lentil mixture. Cook, uncovered, stirring occasionally, until lentil mixture is thickened, about 5 minutes. Garnish with chopped cilantro; serve hot.
