How to Make It
Light a grill. In a medium saucepan, combine the water, ginger, honey, ketchup, tamarind concentrate, chipotle chiles, smashed garlic and cider vinegar and bring to a boil, stirring. Simmer over low heat until thickened, about 20 minutes. Strain the sauce and season with salt.
Meanwhile, in a bowl, mix the minced garlic with the parsley and orange zest. Season with salt and pepper.
Season the steak with salt and pepper and grill over high heat until well-browned and an instant-read thermometer inserted into the thickest part registers 125° for medium-rare, 5 minutes per side. During the last 2 minutes of cooking, liberally brush the steak with the tamarind glaze.
Transfer the steak to a cutting board and let rest for 5 minutes. Thinly slice the steak across the grain on the diagonal and garnish with the orange gremolata. Serve, passing any remaining glaze at the table.