Gather all the ingredients. Thoroughly wash the vegetables. Grate the carrots, finely dice the garlic and cut the bell peppers and onions into cubes. Mix the water and cornstarch together.
In a heavy bottom saucepan to avoid burning, cook the tuna flakes alone for about 2 - 3 minutes on medium heat stirring frequently. After, add in the vegetables and continue cooking for 2 minutes, stirring as and when needed.
Next, add in all the seasoning, cornstarch and water mixture and butter, stir thoroughly and cook for the last 3 - 4 minutes on low heat. When done, take of the heat and allow to cool completely. Use for the intended purpose. This filling can be refrigerated for up to 1 week and frozen for up to 1 month in a zip lock bag. Just reheat for a few minutes before use.
