Stir-fried crab with ginger and scallion

Ingredients

• 2 live crabs (about 600 g each)
• 50 g ginger (thick slices)
• 6 scallions (cut into 5 cm pieces)
• 3 cloves garlic (smashed)
• 2 tbsp light soy sauce
• 1 tbsp oyster sauce
• 1 tbsp Shaoxing wine
• 1 tsp sugar
• 1 tbsp cornstarch (mixed with 2 tbsp water)
• 1/2 cup chicken stock
• 3 tbsp vegetable oil