1. Combine stock, oyster sauce, soy sauce, sherry, and brown sugar in a bowl and set aside.
2. Heat wok to high heat and add oil, swirling to coat sides. Once hot, add garlic and chilli. Cook, stirring for 30 seconds.
3. Add the spinach and stir-fry for 1 minute then quickly add the sauce and stir-fry for a further 3 minutes or until spinach has darkened.
4. Remove from heat, add a light squeeze of lime juice and drizzle sesame oil.