Preheat the oven to broil (510F).
Combine salt, pepper, and beaten eggs in a bowl. Mix well and then set aside.
Heat an oven-safe frying pan or skillet in a stove top. Pour-in the cooking oil.
Once the oil becomes hot, saute the onion and zucchini for 2 to 3 minutes.
Add the tuna. Cook for 2 minutes.
Pour-in the beaten eggs. Gradually stir to distribute the ingredients. Cook in low to medium heat for 4 to 6 minutes.
Turn off heat from the stove top and then place the pan inside the oven. Broil for 5 to 7 minutes or until the top part of the omelet is done.
Serve for breakfast.
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