In a non-stick skillet, drizzle with olive over over medium heat and add chopped leeks. Saute until leeks are softened and cook through then add them to a large bowl and set aside.
Place the cubed fish in a food processor and pulse until fish is ground but not mushy and add fish to the same bowl with the leeks along with egg, 1/2 cup panko, garlic, chopped parsley, lemon zest and spices. Mix everything together and set aside.
Drizzle enough canola oil to coat the bottom of a wide pan and bring to medium-high heat. Form mixture into 10-12 patties and coat each fish cake with remaining panko on each side.
Fry fish cakes for 4-5 minutes on each side until golden brown and garnish with an extra sprinkle of salt.
To make the tomato sauce, in a small pot saute chopped shallot in olive oil until softened, about 2-3 minutes. Then add garlic and cumin and cook for another minute. Add in tomato sauce and salt and pepper and stir together, cooking for 10 minutes until heated through. Once done, set aside.
For he horseradish sauce, stir together the horseradish, mayonnaise, lemon juice, salt and pepper and taste for seasoning.
Serve fish cakes along side sauces and lemon wedges.