Step 1

Heat the vegetable oil in a deep skillet over medium heat. Add the steak and cook until browned on both sides but not overcooked. Remove from the skillet and set aside.

Step 2

In the same skillet, add more oil and sauté the sliced onion until softened. Then, add the garlic, tomatillos, pasilla chiles, and broth. Cook for about 5 minutes, until the chiles are tender.

Step 3

Use an immersion blender to blend everything in the skillet until smooth, or transfer to a regular blender to blend, then return to the skillet. Then, pour in 1 cup of liquid.

Step 4

Add the steak back into the skillet, followed by the cooked potatoes. Simmer until the sauce thickens slightly and the flavors meld together. Adjust seasoning with salt if needed.