Blackened Tuna with Tangy Mustard Sauce

Ingredients (14)

• 0.5 tsp salt optional
• 0.5 tsp garlic powder
• 1 tsp black pepper
• 0.5 tsp cayenne pepper optional
• 1 tsp dried thyme dried
• 1 tsp dried oregano dried
• 1 tsp chili powder
• 1 tbsp paprika
• 1 nonstick cooking spray
• 0.5 cup plain Greek style yogurt non-fat
• 1 lbs tuna filets divided into 4 4-oz filets
• 0.25 cup Dijon mustard
• 1 tbsp soy sauce
• 1 tbsp fresh parsley chopped