Toast the berbere: combine all spices in a large dry skillet over medium heat and stir occasionally for 4 to 5 minutes until fragrant, which activates the flavors. Set aside.
Season the drumsticks with salt and a little of the berbere. Heat the oil in a Dutch oven or braising pan over medium-high; brown the chicken about 4 minutes per side until golden, then remove.
Wipe the pan, reduce heat to medium, and add the onions with no oil. Cook 30 to 35 minutes, stirring occasionally, until pink, dried out, and sticking to the pan somewhat.
Preheat the oven to 375°F (190°C).
Add the garlic, ginger, ½ cup berbere, stock concentrate, niter kibbeh, and tomatoes. Cook 2 minutes, then add 1 cup water. Return the chicken, cover, and braise until the meat reaches 165°F (73.9°C); add water in small amounts if it dries.
Slit and nest the eggs into the sauce so it can penetrate. Serve hot with injera.