Easy Korean Party Food / Braised Beef Ribs "Galbi-zzim"

Ingredients
1kg Short ribs
1 can Korean pear juice (use only 150ml) or 1/3 ground pear
100ml dark soy sauce
100ml mirin (flavoured rice wine)
200ml to 300ml water (water volume may vary depending on cooking time, type of pot, etc.)
some ground ginger
1 T grated garlic
3 potatoes (medium-sized)
1/2 carrot
10 Chestnuts, peeled