Heat the oil in a large skillet over medium heat. Gently sauté the onion and pepper until tender, about 5 minutes. Add the garlic and sauté for 1 more minute, until fragrant.
Add the squash and sauté for 5 to 7 minutes, until cooked but still a little firm.
Toss the squash with the salt and chili powder, then top with the cilantro and serve immediatel