Heat one tablespoon of the olive oil in a 4-5 quart Dutch oven or stock pot over medium until shimmering.
Add the onion and saute until soft and translucent (about 6 minutes).
Scoot the onions to one side and add the remaining one tablespoon of olive oil to the cleared side. Spoon the curry paste, ginger paste, lemongrass paste (if using), and garlic powder over the oil, and stir until fragrant. Mix into the onions.
Add the broth and the pumpkin puree, and mix thoroughly.
Raise the heat to bring the soup to an active simmer for 10 minutes.
Turn heat to low. Taste the soup and add salt by the big pinch until flavorful.
When the soup and completely stopped bubbling, whisk in the coconut milk.
Add a splash (or squeezof lemon or lime juice and taste. Adjust with additional salt, if necessary.
Serve with optional toppings.
Leftovers keep well for several days in the fridge.
