Add tarragon, salt, and black pepper to the beaten eggs. Set aside.
Combine butter and onion in a heat-resistant form. Cover and microwave for 3 minutes. Remove the onion dish from the oven and add the potatoes, garlic, and zucchini. Cover and microwave again for 10 minutes, stopping cooking twice and stirring vegetables.
Pour the beaten eggs over the vegetables, put in the microwave for 3-5 minutes. Meanwhile, preheat the oven with grill function.
Remove the tortilla from the microwave and place it under the grill. Bake until golden brown.
Cut the finished tortilla into portions and serve immediately.