Heat the avocado oil in a large pot or Dutch oven over medium heat. As the oil warms up, it will start to shimmer. This indicates it’s ready for the next step. Don't rush this process; a well-heated oil enhances the flavor of the soup.
Add the onion and sauté, stirring occasionally. You'll want the edges to become golden brown, which usually takes about 5 to 8 minutes. This caramelization will bring out the natural sweetness of the onion.
Introduce the garlic and mushrooms to the pot. Continue cooking for another 3 minutes. Watch for the mushrooms to begin sweating; they’ll release their moisture and add depth to the broth.
Now it’s time to stir in the remaining ingredients. Add the chicken broth, coconut milk, chopped chicken breast, grated ginger, chopped lemongrass, maple syrup or sugar, fish sauce, lime zest, lime juice, and red curry paste.
Stir everything together thoroughly. You want to ensure that the curry paste is well incorporated into the broth. Cover the pot and bring the mixture to a full boil. This step is crucial as it allows the flavors to meld.
Once boiling, reduce the heat to a simmer. Let it cook for about 20 minutes. During this time, your kitchen will fill with the most incredible aroma. You want the chicken to be cooked through and the soup to become aromatic.
After the cooking time, remove the pot from heat. Carefully discard the pieces of lemongrass before serving; they have done their job in flavoring but aren’t pleasant to eat.
Serve the soup in big bowls. I love to garnish each bowl with a wedge of lime and fresh herbs like cilantro. This adds a pop of color and a burst of freshness with every spoonful.
Enjoy your Thai Tom Kha Gai warm! It’s a dish that’s meant to be shared with friends and family, creating memories that linger long after the meal is over.