What is the best way to clean a roasting tray/baking tray that has sauce burned on to it? I made this recipe last week - chicken wings roasted in a marinade of soy sauce, brown sugar and white wine vinegar. It was delicious but lots of the marinade has burned onto my baking tray, and I'm struggling to get it clean. 

I put it in to soak immediately, scrubbed and then tried washing powder, but it is still very firmly stuck on. Does anyone have any cleaning ideas that might help me in this case?
Half fill it with water, then put in on the stove top over a medium heat.  Work the burnt-on bits with a wooden spoon or spatula as the water starts to boil.  You should be able to soften it up and be able to get it off then.