Pour the oil into a medium-sized pan and heat it over medium flame until hot.
Slice the onions and add them to the pan. Cook for 4 to 5 minutes, stirring occasionally, until they soften and begin to turn golden.
Stir in the garlic paste and whole or slit green chillies. Sauté the mixture for 1 minute until aromatic.
Sprinkle in the salt, chilli powder, and turmeric powder. Mix well and allow the spices to cook for about 3 to 4 minutes, stirring occasionally so they don’t stick.
Add the canned tomatoes and stir to combine. Let the mixture cook for 4 to 5 minutes until the oil begins to separate from the masala.
Finally, drain and add the canned tuna to the pan. Stir gently to combine and let it simmer for another 5 minutes, allowing the flavours to blend.
