Heat the pan (don't use non-stick) over medium heat with just the onions in it.
Sweat out some of the moisture for several minutes while stirring constantly.
Once they become translucent add in the niter kibbeh or oil and saute a few more minutes, add in the garlic and saute a bit more.
Add in the cardamom and berbere as well as a few tablespoons of water. Reduce the heat and continue to stir for about 10 minutes. (add water to avoid sticking if necessary)
Add 1/4 cup of water and the lentils. Saute, stirring constantly until the water is absorbed. You want to let the lentil scorch a bit at the bottom of the pan, but not burn, and you scrape them up and stir. Continue adding water 1/4 cup at a time until the lentils are fully cooked and you have a nice wat consistency. Adjust the seasoning adding salt and sugar to taste.