Heat the olive oil in a large pot over medium heat. Add the sliced onions and cook, stirring often, until they soften and turn golden, about 8 minutes.
Stir in the garlic and ginger. Cook for 1 minute until fragrant.
Add the berbere spice and tomato paste. Stir for 30 seconds to coat the onions and release the spice aroma.
Pour in the vegetable broth and add the rinsed lentils and salt. Bring the mixture to a boil.
Reduce the heat to low, cover the pot, and simmer for 20 minutes, stirring once or twice, until the lentils break down and the stew thickens.
Remove the pot from the heat. Ladle the stew into bowls and top each serving with chopped parsley.