Place sliced meat in to a shallow bowl and season with salt, black pepper and chilli flakes. Pour the lime juice over and turn meat until evenly coated. Cover and refrigerate for 30 minutes.
In a blender or food processor, combine tomatillos and chillies. Purée for 20 seconds.
Heat 1 tablespoon oil in a large frying pan over medium high heat. Carefully pour in tomatillo mixture. Cook, stirring frequently, for 5 minutes. Stir in beef stock. Reduce heat and simmer for 20 to 30 minutes or until mixture coats a spoon. Transfer mixture to a serving dish.
Heat remaining 2 tablespoons of oil in a large frying pan over high heat. Stir in 1/3 of the beef, and sauté for 1 minute. Transfer to serving dish. Repeat with remaining beef. Meanwhile, heat tortillas in the oven or microwave, according to package instructions.
To Serve: Place two tortillas on top of each other. Add desired amount of meat, spoon over some tomatillo mixture. Top with chopped onions, tomatoes, avocado and coriander. Garnish with a wedge of lemon, to be squeezed over taco before eating.
Used different ingredients.
My family comes from Mexico and my grandmother made a similar recipe which I always loved. I'm so thrilled to have found this one. I used fresh tomatillos instead of canned and more limes(key limes make it even better if you can get them). Great recipe! - 29 Sep 2008
Made it vegetarian.
I used bottled salsa and that takes all the work out of prepping the sauce, leaving just the time it takes to cook it down. This sauce is made with Tomatillos and jalapenos-it came out great! This is a recipe worth trying. - 29 Sep 2008
by MAGGIE MCGUIRE
The tomatilla sauce was a lot of work for the end result. Also, canned tomatillas were very difficult to find...I used fresh instead. This was so-so - not great, but not bad. - 29 Sep 2008