Preheat the oven to 350°F (175°C).
In a large bowl, combine the drained tuna, frozen peas, bell peppers, onions, celery, carrots, and minced garlic.
In a separate small bowl, mix together the mayonnaise, Greek yogurt, Dijon mustard, lemon juice, dried dill, salt, and pepper.
Pour the mayo-yogurt mixture over the tuna and vegetable mixture. Stir to combine.
Transfer the mixture into a greased casserole dish.
Sprinkle the shredded cheddar cheese evenly over the top of the casserole.
In a small bowl, mix together the bread crumbs with a drizzle of olive oil to moisten them slightly. Sprinkle the bread crumbs evenly over the cheese.
Bake for 40 minutes, or until the casserole is bubbly and the bread crumbs are golden brown.
Remove from the oven and let it cool slightly before serving.
Serve hot and enjoy!