Looks perfect. Flank is actually my favourite steak, have been using the same asian marinade for 30+ years. Lots of soy, sesame oil,, 3 or 4 tbsp of hoisin sauce, 2-4 cloves minced garlic, 3 or 4 tbsp sambal olek or sirracha, juice and zest of a lime, 4-5 rough chopped green onions, big knob...