Season the fish with salt and pepper, then, coat each with flour.
Heat oil in a frying pan over medium-high heat.
Cook the fish for about 2 minutes per side, or until the fish is opaque and slightly browned. Transfer to a plate and set aside.
Add onion, ginger and garlic to the same pan and cook for 1 minute. Stir in soy sauce, vinegar, brown sugar, chilli sauce and chicken broth.
Cook for another minute to allow sugar to dissolve. Stir in cornstarch and cook until sauce thickens slightly.
Reduce heat; return ribbonfish and add bell pepper to the pan and cook for another 3 minutes, or until fish is heated through.
Season with salt and black pepper.
Transfer to serving platter and serve warm.
Serving Suggestions: Garnish with scallion greens and serve with a soy sauce for dipping.