1. Heat 2-3 tablespoons (30-45 ml) of oil in a large pan or wok over medium-high heat, approximately 200°C (400°F).

2. Add 2 sliced bell peppers and cook until tender, about 5 minutes.

3. Remove the peppers from the pan and set aside.

4. In the same pan, add 250g (8.8 oz) of beef strips and cook until browned, about 5-7 minutes.

5. Add 1 teaspoon of sambal oelek, 1/2 teaspoon of salt, and 1 tablespoon of potato starch to the pan and stir to combine.

6. Cook for an additional 1-2 minutes.

7. Add 2 tablespoons of lime juice, 1 tablespoon of soy sauce, 1 tablespoon of hot chili sauce, and 2 teaspoons of red curry paste to the pan.

8. Stir to combine, then add the cooked bell peppers back into the pan.

9. Pour in 250ml (8.4 fl oz) of coconut milk and bring the mixture to a simmer.

10. Reduce the heat to medium-low, approximately 150°C (300°F), and let cook for 10-15 minutes or until the sauce has thickened.

11. Stir in 100g (3.5 oz) of fresh spinach and cook until wilted.

12. Serve hot, garnished with additional spinach if desired.