Preheat your oven to 425 degrees f.
Place your pepper halves, cut-side up, in a large baking dish.
Lightly spray or mist with a bit of avocado oil or olive oil cooking spray and season lightly with sea salt and pepper. Roast for 15 minutes, or just until the peppers start to soften.
Meanwhile, in a large bowl prepare your tuna stuffing.
Combine the tuna with celery, onions, peas, yogurt, lemon zest and juice, mustard, and half of the cheese. Season with sea salt and pepper to your taste then stir gently to combine.
Once the peppers are softened a bit, carefully remove them from the oven then evenly divide your tuna stuffing among each one.
Top evenly with the remaining shredded cheese.
Return to the oven and bake for about 15-20 minutes more, or until the cheese is melty and your stuffing is hot throughout.
Garnish with chopped fresh parsley or dill and serve with your fresh lemon wedges.
Enjoy!