Peel and thinly slice the red onions. Warm a deep frying pan or wok on a medium heat for 1 min, then pour in ½ tbsp olive oil. Add the onions with a good pinch of salt and pepper. Fry for 8 mins, stirring occasionally, till glossy and starting to brown. If the onion browns too quickly, turn the heat down and add a few tbsp water to the pan.

While the onions cook, peel and grate or crush the garlic. Pull the kale leaves off the cores, then chop the leaves. Drain and rinse the butter beans.

When the onions have cooked for 8 mins, add the garlic and 1 tbsp each red wine vinegar and Spanish seasoning to the pan. Cook, stirring, for 2-3 mins.

Meanwhile, warm a frying pan on a medium heat for 1 min. Rub each hake fillet with 1 tsp olive oil and some salt and pepper. Carefully place the fillets in the frying pan, skin-side down. Fry for 3-5 mins till the skin has crisped up, then gently turn them over and cook for 3-5 mins till the fish is cooked through – it will be opaque and flake easily when pressed with a fork. If you prefer to grill your fish, see our tip below.

Add the kale to the pan of onions, along with the butter beans. Pour in 250ml cold water, stir and cook for 5 mins, stirring often, till the kale has softened and the beans have warmed through. If the fish isn't ready yet, turn the heat off under the pan and set aside till the hake is ready.

Taste the kale and beans and add more salt, pepper or red wine vinegar if you think it needs it. Divide between 2 warm plates, top with a hake fillet each and serve.