How to Make It
In a large, shallow dish, combine the garlic, thyme, rosemary, wine, onion and olive oil. Add the hanger steaks and turn to coat thoroughly. Cover and refrigerate for at least 4 hours or overnight.
In a food processor, pulse the garlic, parsley, oregano, vinegar, lemon juice and olive oil until the herbs are pureed. Scrape into a bowl and season with salt and pepper. In a large skillet, cook the bacon in 2 batches over moderate heat until crisp, about 8 minutes. Drain on paper towels and let cool, then finely chop. Pour all but 2 tablespoons of the bacon fat from the skillet.
Light a grill. Scrape the marinade off the steaks and season them with salt and pepper. Grill the steaks over a hot fire until charred all over, about 10 minutes for medium-rare meat. Transfer to a cutting board and let rest for 5 minutes.
Meanwhile, heat the bacon fat in the skillet. Add the chimichurri and bring to a simmer over high heat. Remove from the heat and stir in the bacon. Pour the sauce into a serving bowl. Carve the steaks crosswise into thick slices and serve immediately with the chimichurri.