Start by cooking the rice according to package directions using 1 1/3 cups water for 2/3 cup rice, then set aside to cool slightly. While the rice cooks, slice the mushrooms into 1/4-inch pieces, cut the chicken breast into 1/2-inch bite-sized cubes, finely dice the onion and bell pepper, grate the fresh ginger, and measure out all your liquids and pastes. Having everything prepped and ready will make the cooking process smooth and prevent any scrambling once the pot gets hot.

Heat the neutral oil in a large pot over medium-high heat until shimmering. Add the sliced mushrooms in a single layer and cook without stirring for 3-4 minutes until golden and caramelized on the bottom, then stir and cook another 2 minutes until tender. Transfer the mushrooms to a bowl. In the same pot, add the chicken cubes and sear for 4-5 minutes, stirring occasionally, until the outside is no longer pink. Transfer the cooked chicken to the bowl with the mushrooms. I like to sear the mushrooms first because they release their moisture and won't brown if the chicken is in the pot—this small step really deepens the soup's flavor.

In the same pot with the remaining oil and fond, add the diced onion and bell pepper over medium heat. Cook for 3-4 minutes, stirring occasionally, until the vegetables soften and become fragrant. Add the grated ginger and cook for another 30 seconds until very fragrant. Return the seared mushrooms and chicken from Step 2 to the pot, stirring to combine with the aromatics.

Pour the 4 cups of chicken broth into the pot and bring to a simmer over medium heat. Once simmering, add the fish sauce, Worcestershire sauce, and lemongrass paste, stirring well to dissolve the paste. Simmer for 5 minutes to let these flavors meld together and develop depth. The lemongrass and fish sauce are the backbone of Thai flavor here, and giving them time to infuse into the broth makes a real difference.

While the broth simmers, whisk together the red curry paste, Sambal Oelek chili paste, tomato paste, and cornstarch in a small bowl until smooth and well combined—this prevents lumps when you add it to the hot soup. Once the 5-minute simmer is complete, stir in the half and half and coconut milk, then slowly pour in the curry paste mixture while stirring constantly. Simmer for 3-4 minutes, stirring occasionally, until the soup thickens slightly and coats the back of a spoon. The cornstarch acts as a thickener and helps create a silky, cohesive texture.

Remove the pot from heat and stir in the lime juice, fresh cilantro, brown sugar, and salt and pepper to taste. The lime juice brightens all the rich, creamy, spicy flavors while the cilantro adds fresh aromatics. Taste and adjust seasonings as needed—you may want a touch more salt, lime, or chili paste depending on your preference.

Divide the cooked rice from Step 1 into individual serving bowls, then ladle the hot soup from Step 6 over the rice. Garnish each bowl with fresh lime wedges and extra cilantro if desired. Serve immediately while hot.