Place 6 tablespoons chickpea flour in a medium bowl. Whisk in broth by the tablespoonful until a smooth paste forms. Slowly add remaining broth, whisking constantly. Pour mixture into a 12-inch-wide saucepan (big enough to hold all dumplings without clumping together). Bring to a boil, whisking frequently. Reduce heat, cover, and simmer over medium-low heat while making dumplings. Season to taste.

Sift remaining 1/2 cup chickpea flour, rice flour, baking powder, sugar, and garlic salt into a medium bowl. Add egg, milk, and oil. Stir until uniform. Set aside.

Whisk sauce again until smooth (some foaming or separation may have occurred); then stir in chicken and frozen vegetables. Bring to a boil, and then reduce heat to a simmer. Drop dumpling dough by the tablespoonful into simmering stew, leaving an inch between each (they will double in size). Cover and simmer for 8–10 minutes, until dumplings are firm and cooked through (not wet when cut in half). Spoon into bowls and serve.