To make curry paste: Toast coriander seeds, fennel seeds, and cinnamon stick in dry skillet over medium heat several minutes, or until they become fragrant. Remove seeds and cinnamon stick from skillet, place in blender or food processor with remaining ingredients, and purée.
To make fish: Cut broccoli florets into bite-size pieces. Sear 3 tablespoons curry paste in large wok over medium-high heat 2 minutes. (Place remaining 1 to 1 ½ cups curry paste in air tight glass jar and store in refrigerator up to ten days.) Add coconut milk and vegetable stock and reduce slightly over medium heat15 minutes.
Add broccoli, tomatoes, and snow peas to curry stock and stir well. Simmer 5 minutes.
Heat oil in a skillet over medium heat and cook fish 5 to 7 minutes per side. Distribute curry in serving bowls. Add fish, top with scallions, chile pepper, cilantro, and black sesame seeds.