Healthy Mediterranean Baked Fish

Ingredients

• 1 cup red onion, sliced
• 4 cloves garlic, whole (papery shells removed)
• 10 oz cherry or grape tomatoes
• 2 cups mushrooms, sliced
• 1 tbsp + 1 tsp olive oil, separated
• 1 lemon, sliced
• 1 lb halibut fillets or another mild white fish
• salt and pepper, to taste
• 1/2 tsp dried oregano
• 125ml black olives, drained and rinsed
• 1 tbsp feta cheese (I use goat’s milk feta)
• chopped fresh parsley, for serving