Bakso - Indonesian meatball soup

Ingredients

• 700 grams marrow bones (or beef shank)
• 1 litre water
• 1 onion
• 4 garlic cloves
• 5 celery stalks
• 1 cm fresh ginger (optional)
• 100 grams rice noodles
• 100 grams egg noodles
• 4 boiled eggs
• 2 pak choi
• spring onions
• a splash of sweet soy sauce (ketjap) (for serving)
• sambal oelek (for serving)
• crispy fried onions (for serving)
• 500 grams minced beef
• 3 garlic cloves
• 1 teaspoon salt
• 0.5 teaspoon white pepper
• 1 teaspoon sugar
• 1 egg white
• 100 grams tapioca flour (or cornstarch)
• 100 ml ice-cold water