interesting! I never heard of green mango jam used in a filipino BBQ recipe. Must be something new or from a different part of the Philippines!
The only way I know how to make filipino BBQ is to marinate the meat overnight in soy sauce, vinegar, smashed or minced garlic cloves, black pepper and garlic salt. When you're done marinating, weave the thin strips of meat onto a wet bamboo skewer or for larger pieces, simply throw on a grill.
Green mangos are eaten quite often in the Philippines - especially in the Pangasinan area which is in just north/northwest of Manila. In this area, they eat unripened or green mangoes with bagoong - a salty greyish-brown anchovy condiment or alamang - a salty bright (almost neon) pink shrimp condiment. Pangasinan is the bagoong capital of the philippines and is used in many of the area dishes.
May I ask where you got your recipe? I'd be interested in checking it out and others to try!