Line a sheet pan with foil. Adjust oven rack close to broiler, if necessary.
In a medium saucepan with lid, combine sorghum mix and water, cover, and bring to a boil. Reduce heat and simmer for 15 to 17 minutes or until most all of the moisture has been absorbed. Remove from heat and set aside.
Halve zucchini lengthwise and scrape out pulp with a spoon. Place zucchini in a microwave-safe dish, cover with plastic wrap, and microwave on HIGH for 4 minutes. Let stand covered until ready to stuff.
In a large skillet, heat two teaspoons of olive oil over medium-high heat and cook sausage for 3 minutes or until starting to brown. Add onion and continue to sauté for 4-5 more minutes or until the sausage is cooked through and the onion is tender. Stir cooked sorghum into the sausage mixture. Set aside.
In a small bowl, stir together breadcrumbs, Parmesan cheese, and olive oil until thoroughly mixed. Set aside.
Place zucchini halves on a lined sheet pan. Divide sausage mixture evenly into prepared zucchini, letting each portion mound slightly. Top with the breadcrumb mixture and broil for two to three minutes or until the crumb topping becomes toasted and melty. Serve immediately.