Heat sesame oil in a large pot over medium heat. Add diced onion, garlic, and ginger. Sauté until fragrant, about 2 minutes.
Pour in the broth, soy sauce, rice vinegar, and sriracha. Bring to a boil.
Add mushrooms, spinach, and shredded carrots. Reduce heat to a simmer.
Carefully drop in the frozen potstickers. Cook for 5-7 minutes or until heated through.
Ladle into bowls, garnish with sliced green onions and sesame seeds, and serve hot.