In a heavy-based frying pan, heat 2 tablespoons of olive oil over medium-high heat. Add cubed beef chuck in batches, searing for 4-5 minutes until browned on all sides.

In the same pan, add the finely diced brown onion, minced ginger, minced garlic, and optional lemongrass. Sauté for 2-3 minutes until the onions are translucent.

Stir in the yellow curry paste and cook for 30 seconds. Pour in the canned coconut milk, followed by the brown sugar and fish sauce. Mix well and return the browned beef to the mixture.

Reduce the heat to low, cover the pan, and let it simmer for 2 hours.

After 2 hours, remove the lid and increase the heat to medium-high. Let the curry simmer uncovered for another 15 minutes, or until sauce thickens.

Serve hot over fluffy jasmine rice, garnished with lime wedges and optional toppings like roasted crushed peanuts or fresh Thai basil.