In a large pot, heat the vegetable oil over medium heat.
Add the diced onion and sauté until translucent, about 5 minutes.
Stir in the minced garlic and grated ginger, cooking for another minute until fragrant.
Add the red curry paste and cook for 2 minutes, stirring frequently.
Pour in the coconut milk and vegetable broth, stirring to combine.
Add the soy sauce and lime juice, then bring the mixture to a simmer.
Add the sliced carrots, diced bell pepper, and snap peas. Cook for about 10 minutes, or until the vegetables are tender.
While the soup simmers, prepare the dumplings by combining the all-purpose flour, baking powder, and salt in a bowl.
In another bowl, whisk together the milk and egg. Gradually add the wet ingredients to the dry ingredients, stirring until just combined.
Drop spoonfuls of the dumpling batter into the simmering soup.
Cover the pot and let the dumplings steam for about 10 minutes, or until they are cooked through.
Stir in the fresh spinach just before serving.