In a mixing bowl, combine all-purpose flour, baking powder, and salt. Gradually add vegetable oil and water while mixing until a dough forms.
Knead the dough on a floured surface for about 5 minutes until smooth. Cover with a cloth and set aside.
In a large saucepan or pot, heat 1 tablespoon of vegetable oil over medium heat. Add chopped onion and sauté for 3-4 minutes until translucent.
Add minced garlic and ginger, sautéing for another minute until fragrant.
Stir in the red curry paste and cook for an additional 2 minutes.
Pour in the vegetable broth and coconut milk, then add soy sauce and lime juice. Bring to a simmer.
While the broth simmers, roll out the dumpling dough on a floured surface to about ¼ inch thick. Cut into small circles (about 2 inches in diameter).
Drop the dumpling circles into the simmering soup. Allow them to cook for about 10 minutes, or until they are fluffy and cooked through.
Add baby spinach to the soup and stir until wilted.
Ladle the soup into bowls, garnishing each with fresh cilantro and a lime wedge.