Thinly slice the Beef Sirloin against the grain into bite-size strips and pat dry.
Peel and finely chop the Red Onion; dice the Tomato; mince the Garlic and grate the Ginger; thinly slice the Green Chili and finely chop the Rosemary.
In a bowl, toss the beef with a generous pinch of Fine Salt, freshly ground Black Pepper, and the Berbere Spice Blend until evenly coated; let sit 10–15 minutes to absorb the flavors.
Heat a large skillet or cast-iron pan over medium-high heat and add the Niter Kibbeh until it shimmers and is fragrant.
Working in a single layer (do this in batches if necessary), add the beef to the hot pan and sear without moving for 1–2 minutes to develop a brown crust, then stir and cook another minute until mostly browned; remove the beef to a plate and keep warm.
Add a little more Niter Kibbeh if the pan is dry, then add the Red Onion and cook, stirring, until softened and edges begin to caramelize, about 4–6 minutes.
Stir in the minced Garlic, Ginger, Green Chili, and Rosemary and cook 1 minute until aromatic, then add the Tomato and cook until it breaks down and creates a saucy base, about 4–5 minutes.
Return the seared beef to the pan, toss to combine, and simmer together for 2–3 minutes so the flavors meld; taste and adjust with more Fine Salt or Black Pepper as needed.
Turn off the heat and let the tibs rest a minute so the sauce slightly thickens. Serve immediately on Injera, using pieces to scoop up the beef and its fragrant sauce.
