Combine the chili powder, salt, garlic powder, onion powder, cumin and black pepper in a small bowl. Stir to mix well.
Heat the canola oil in a large skillet over medium-high heat. Add the ground beef and the prepared seasoning mix. Stir to combine.
Cook the ground beef until browned, approximately 5 minutes, stirring frequently and breaking up any large pieces with a wooden spoon or spatula.
Add the tomato sauce and water, stir well to combine.
Lower the heat to medium-low, cover and cook about 15 minutes, stirring occasionally. If the sauce is boiling too vigorously, lower the heat a bit.
While the ground beef cooks, preheat the oven to 350°F
When the ground beef is done, remove it from the heat and allow it to cool a bit.
Build the fillo taco cups - Fill the fillo cups with about 1 tsp. of ground beef and arrange them on a baking sheet lined with parchment paper.
Bake the fillo taco cups for 5 minutes or so to warm through.
Remove the baking sheet from the oven. Add a pinch of cheese to each taco cup. Place them back in the oven and bake 2-3 minutes until the cheese melts.
Garnish and serve - Add a dollop of sour cream and garnish each cup with a few pieces of diced tomatoes and green onions. Arrange the fillo taco cups on a tray and serve.