Heat a pot to medium and spray with olive oil. Add celery, bell peppers and onion. Add crushed red pepper and oregano and season with salt and pepper to taste. Cook for 5 minutes. Add garlic and quinoa and cook for one more minute.
Add 1 ⅓ cups water. Bring to a simmer. Reduce heat to low and cover. Cook for 30 minutes, adding in spinach during the last two minutes of cooking. Remove from heat and allow to sit for 5 minutes covered. Fluff with and stir in parsley.
Meanwhile, spray a small skillet with olive oil spray. Add sausages and cook until browned. (About 10 minutes – according to package directions.) Remove from heat and . When cool enough to handle cut crosswise.
Toss sausages with quinoa and drizzle with red wine vinegar. Serve warm.