Step 1

Preheat the oven to 350 degrees F.

Step 2

Grease a 9x13-inch baking dish.

Step 3

In a large skillet over medium-high heat, cook and stir the beef until it is browned and crumbly, about 5-7 minutes. Drain the excess grease.

Step 4

Add the chili powder, the oregano, the salt, and the black pepper to the beef and mix well.

Step 5

In the prepared baking dish, add a layer of the cooked rice, a layer of the beef mixture, a layer of the mushrooms, and a layer of the green pepper slices.

Step 6

In a large saucepan, add the sugar and the cornstarch and mix well.

Step 7

Add the cold water, the white vinegar, the ketchup, the salt, and the black pepper to the sugar mixture. Bring to a boil and cook, stirring constantly, until it thickens, about 2 minutes.

Step 8

Add the sauce mixture on top of the green pepper layer.

Step 9

Bake, uncovered, until it is heated through, about 30 minutes.

Step 10

Plate and serve.