In a heavy large saucepan, heat canola oil over medium high heat. Saute the onions until translucent. Stir in minced garlic, ginger and Thai red curry paste and sauté until fragrant. Sprinkle with flour and stir in.
While the pan is simmering and after the potatoes are fork-tender, carefully submerge the fish pieces into the coconut broth. Cook for about 15 minutes longer or until fish flakes easily with a fork. (Gently stir/move fish pieces around halfway through.)
Remove pan from heat and pour into a large serving dish. Sprinkle with ½ cup chopped cilantro and serve hot with cooked Jasmine rice, lime wedges and additional cilantro leaves, if desired.