Slice off the stem of the squash. Starting at the top of the squash, slice the squash lengthwise, to create two long halves.
Remove the seeds and guts. Brush some olive oil onto the squash and sprinkle with salt and pepper.
Place squash halves cut side down on the baking sheet and roast for 30-50 minutes, depending on how large your squash is.
Check on it around 25 minutes of baking time--it's ready when it is tender and easy to scrape the strands with a fork.
While the squash is roasting, prepare the filling. In a mixing bowl add the chopped avocado, onion, tomato, black beans, and cilantro. Season to taste with lime juice, salt, pepper, and red pepper flakes.
Remove squash from the oven and flip over. Sprinkle on, to taste, some chili powder, cumin, oregano, salt, and pepper.
Fill each half of squash with the vegetable filling. Enjoy!