In a large pot, heat sesame oil over medium heat. Add frozen potstickers and cook for 3-4 minutes until golden brown, turning occasionally. Remove from the pot and set aside.
In the same pot, add the coconut milk, chicken broth, red curry paste, soy sauce, fish sauce, lime juice, and brown sugar. Stir well and bring to a simmer.
Add sliced mushrooms and cook for 3-4 minutes until tender. Stir in the baby spinach and let it wilt.
Return the cooked potstickers to the soup and simmer for another 2-3 minutes to heat through.
Ladle the soup into bowls and garnish with chopped cilantro, sliced green onions, and a drizzle of Sriracha if desired. Serve hot and enjoy!