To defrost kit components, place kit in refrigerator overnight. Once thawed, remove cubes and sauce packet from kit, Place cubes into clean colander and let sit a few minutes to drain. Open sauce packet and combine sauce and half the onions in a mixing bowl. Mix thoroughly.
Add tuna cubes and toss gently until coated evenly with sauce.
Preheat oven to 350 F. Slice baguette and place on baking sheet in a single layer. Toast in the oven until golden brown, about 5 minutes. Top the bread with green lettuce and sliced tomato. Then layer the mixed poke and sprinkle with the remaining diced onion.