Coat the bottom of a large pot with oil and place over medium
heat. Add onion and sauté until soft, about 5 minutes. Add
garlic, ginger, berbere and cayenne and sauté 1 minutes more.
Add broth, lentils, tomatoes and potatoes. Stir a few times,
raise heat and bring to a simmer. Lower heat and allow to
cook until lentils are very soft and potatoes are tender, about
30 minutes. Stir in spinach and continue to cook just until
wilted, about 2 minutes. Remove from heat and season with
salt and pepper to taste. You can also add a bit more berbere
and cayenne, if desired.