Heat your oven to 140°C/Fan 120°C/Gas 1. Peel and finely chop the shallots. Warm a pan for 1 min, then add ½ tbsp oil and the shallots. Season with a pinch of salt and fry, stirring every so often, for 5 mins till the shallots start to soften.
While the shallots fry, peel and crush or grate the garlic. Finely chop the coriander stalks, setting the leaves aside for later. Drain the black beans.
Stir the garlic and coriander stalks into the shallots. Cook and stir for 1 min, then tip in the black beans and pour in 200ml boiling water. Cover, bring to the boil, then turn the heat down and simmer for 10 mins, stirring every so often, till the beans are soft and have thickened a little. When the beans are ready, take them off the heat but leave them in the pan, lid on, to keep warm.
While the beans simmer, slice a quarter out of the summer cabbage and then finely shred it (see our tip on using up the rest of your cabbage). Set aside.
Tip the flour into a mixing bowl and add 1 tsp each of the dried oregano and cumin and a pinch of cayenne pepper (it’s spicy, so use as much or as little as you prefer). Add a pinch of salt and whisk with a fork to mix everything together.
Add the fish pie mix to the spiced flour and toss to thoroughly coat the fish in the flour.
Wrap the tortillas in foil to make a loose parcel, then pop them in the oven to gently warm for 5 mins.
Warm 1 tbsp oil in a large frying pan or wok over a medium-high heat for 2 mins. Add the floured fish pie mix and fry for 3-4 mins, turning often, till golden and crisp all over.
Taste the beans and add a pinch more salt if you think they need it. Unwrap the tortillas and divide between 2 plates. Top with the cabbage, black beans, crisp fried fish and the coriander leaves. Serve with wedges of lime for squeezing.