Add the 1/2 cup of dry quinoa into a cooking pot with the 1 cup of water and bring to a boil. Then, cover with a lid and turn the heat down to a simmer. Cook until quinoa is tender, about 8 minutes and set aside.
Preheat the oven to 350 degrees Fahrenheit.
Rinse and slice the 1 whole zucchini in half down the middle. Then with a metal spoon, scoop out the inner seeds to make room for the stuffing.
Slice the 1 cup of tomatoes, 1 cup of basil leaves, and 1 cup of brown mushrooms. Add them into a frying pan with a tbsp of water on a high heat and cook for 5 minutes, while stirring.
Add the tomatoes, basil leaves, brown mushrooms, 1 cup of feta cheese, 1/2 tsp of black pepper, 1/8 tsp of sea salt, and 1/2 tsp of garlic powder into the same pot as the quinoa. Mix all the contents together.
Add the mixture into each open zucchini.
Then, place the zucchini's onto a deep baking pan. Add water to the bottom and fill about half way. Then, bake until the zucchini is tender, about 20 minutes. Remove the zucchini's from the baking pan and onto a plate.