Cook Quinoa: In a pot of boiling water, add quinoa and salt. Boil for 15 minutes.
Prepare Vegetables: Chop onion, spring onions (green part), cucumber, and tomato. Place in a bowl.
Mix Dressing: Add salt, pepper, olive oil, and mango balsamic vinegar to the vegetables and mix.
Combine Ingredients: Strain the cooked quinoa and add it to the bowl with the vegetables.
Add Herbs: Finely chop mint and parsley, add to the bowl, and mix well.
Finish Salad: Add lemon zest, mix again, and transfer to a platter.
Serve: Drain the tuna and place it on top of the salad. Drizzle with olive oil and balsamic vinegar.