Char the poblanos all over an open-flame burner or under a broiler. Cool in a covered bowl then peel, seed and slice.
Heat a sauté pan over medium-high heat with oil, 1 turn of the pan. Add onions and garlic, season with salt and pepper, and stir to soften, 5 minutes. Add stock, chipotle in adobo, Worcestershire, Tamari or Liquid Amino, vinegar, sugar and tomato purée. Reduce heat to a simmer and let thicken, about 15-20 minutes.
Heat a cast-iron skillet over medium-high to high heat.
Char tortillas in a dry pan or over an open flame for 30 seconds to 1 minute on each side. Wrap them in a cloth napkin or towel to keep warm.
Season the steak with Kosher salt and coarse black pepper. Add oil to pan, half a turn of pan. Add steaks and cook skirt steak 3 minutes per side or hanger steak 4-5 minutes per side; remove and let rest.
Add another half turn of the pan of oil and the red onions, season with salt and pepper and cook to tender-crisp, 5 minutes. Add the sliced poblanos and toss to combine.
To serve, slice steak against grain and arrange on top of the onions and peppers in the skillet. Serve from pan with barbecue sauce, lime wedges and charred tortillas, with Green Rice
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