This time, I used these cooking tomatoes (roma tomatoes.) You could also use regular tomatoes or canned tomatoes.
I used 1 green and 1 yellow zucchini.
If the tomato skins bother you, peel them. If you're using cooking tomatoes, the skin won't be a problem. Remove the stem and chop into bite-size pieces.
Remove the stem from the zucchini and halve lengthwise. Then slice into 1 cm half moons.
Chop the onion and bell peppers into the same size as the tomatoes.
Heat a thick-bottomed pot over low heat and add the oil from the tuna can. Add the chopped garlic and cook until fragrant. Then add all the vegetables and cook over medium heat. Add the tuna. When all the ingredients are coated with oil, add the oregano and cover the pot and simmer.
When it comes to a boil, reduce the heat to low and continue simmering for about 15-20 minutes, stirring occasionally to prevent burning. You don't need to add water since a lot of liquid seeps out from the vegetables.
When all the ingredients are cooked through and the liquid is reduced, season with salt and pepper.
I made this one with tomatoes, zucchini, eggplant, bell peppers, shiitake mushrooms, canned mix beans, and canned tuna. The beans really work well too.
Here's a variation with cherry tomatoes, zucchini, egg plant, bell peppers, kabocha squash, buna-shimeji mushrooms, onion, and tuna can. Kabocha added some sweetness.
Story Behind this Recipe
I love ratatouille. Adding bacon enriches the flavor, but if you chill it in the fridge, all the fat hardens and will be unpleasant to the palate. So I thought about adding a can of tuna. That's how I made this delicious ratatouille that will stay tasty even after it's chilled and also very rich in flavor. I think it goes well with any summer vegetables and mushrooms except for leafy greens.
You simmer the vegetables with only the oil from the canned tuna and the water from the vegetables. Just be careful not to burn it. I used oregano and coarsely ground pepper, but use whatever spices you like. I recommend lots of pepper.