Cook quinoa according to the instructions, it can also be a few minutes less.
Chop onions, peppers and garlic into small pieces.
Fry the onions in a little oil, add the paprika and garlic as well as the tomato paste and fry with them. Deglaze with the vegetable stock and add the chopped tomatoes. At the end, mix in the tuna and quinoa and season with salt, pepper and cumin.