Make the coconut broth: Melt the coconut oil in a wok or large pan over medium heat. Add the red onion and cook until it starts to become translucent, about 3 minutes.
Add the lemongrass to the wok, along with the ginger, garlic, and red pepper flakes. Cook until fragrant, about 3 minutes.
Pour in the white wine and stir to deglaze the pan. Bring to a simmer and cook until reduced by half, about 5 minutes.
Add the brown sugar, fish sauce, vegetable broth, and coconut milk. Bring to a boil.
Add the clams, return to a boil, and cook for 5-8 minutes, or until all of the clams are fully opened. If any clams remain closed, discard them.
Divide the clams and broth between serving bowls. Garnish with scallions and cilantro and serve with the grilled bread for dipping.