Wash the vegetables and chop into small pieces. Grease an oven tray with extra-virgin olive oil and arrange the vegetables on it. Add salt and drizzle some more extra-virgin olive oil on top.
Bake the vegetables at 200 ºC until they are cooked, which should take about 40 minutes, moving them around a couple of times during the process. (You could fry them, but they’re much better baked in the oven.)
Once they’re done, put them into a large bowl and mix with the strained tinned tuna and some tomato sauce and add cumin to taste. Spoon some of the mixture onto the patty dough and close up into a half-moon, sealing the edges with a fork.
You can either fry or bake the patties. If you bake them, glaze with some beaten egg to give them a lovely golden finish.