In a large pot, heat the vegetable oil over medium heat. Add the diced onion and sauté for about 5 minutes until translucent.
Stir in the minced garlic and ginger, cooking for an additional 1-2 minutes until fragrant.
Pour in the chicken broth and water, then add the soy sauce and sriracha. Bring the mixture to a boil.
Once boiling, carefully add the frozen dumplings to the pot. Reduce the heat to a simmer and cook for 8-10 minutes, or until the dumplings are heated through.
Add the baby spinach and cook for another 2 minutes until wilted.
Stir in the sesame oil and season with salt and pepper to taste.
Serve hot, garnished with sliced green onions.