Cook pasta according to package directions. Drain and toss with olive oil if desired.
Meanwhile, spray a large saucepan with olive oil spray. Add onion and cook for 8 to 10 minutes, until tender. Add quinoa, garlic, oregano, red pepper, black pepper and sea salt. Cook for 3 to 4 minutes, stirring constantly. Add marinara, vegetable broth, olive, sherry and capers. Bring to a simmer. Cover and reduce to low. Cook covered for 30 minutes. Remove from heat and allow to sit covered for another 5 minutes.
Divide pasta among four plates. Top with sauce and garnish with parsley and additional olives.