Bistek Tagalog (Filipino Beef Stew)

800gms Chuck Roast sliced
1/2 cup kalamansi juice
3 tbsp brown sugar
5 tbsp silver swan soy sauce
1 tsp ground pepper
3-4 medium size onions cut into rings
1 tbsp butter
olive oil for browning beef & onions
add more seasoning accdg to your preference...