Mystery solved! Here's how you get juicy and browned meat roll

Ingredients:
pork belly: 2 kg (4 lb)
soft butter: 100 g (3.5 oz)
parsley: 20 g (0.7 oz)
garlic: 7 cloves
salt: 2 g (0.1 oz)
black pepper: 2 g (0.1 oz)
ground coriander: 4 g (0.1 oz)
onion: 2 pc
butter: 30 g (1.1 oz)
onion: 1 pc
green apple: 1 pc
garlic: 2 cloves
sugar: 10 g (0.4 oz)
flour: 15 g (0.5 oz)
cooking cream: 250 g (8.8 oz)
black pepper: 4 g (0.1 oz)
salt: 4 g (0.1 oz)
soy sauce: 30 ml (1 fl oz)