Peel and finely chop the onion. Warm a medium pan over a medium heat for 1 min, then add ½ tbsp olive oil and the onion. Season with a good pinch of salt and pepper. Pop a lid on the pan (or use a baking tray if you don't have a lid) and fry the onion for 5–6 mins, stirring a few times, till the onion starts to soften and look glossy.

While the onion fries, trim the dry ends off the celery stick and dice the celery. Trim, peel and dice the carrot. Halve the pepper, scoop out the seeds and white pith, then finely dice the pepper. Add all the veg to the pan. Pop the lid back on and fry the veg for 5 mins, stirring every so often, till the veg have started to soften but not picked up any colour (if they start to brown, turn the heat down).

While the veg fry, peel and grate or crush the garlic. Drain and rinse the haricot beans.

Stir the garlic into the veg with the bay and most of the thyme sprigs (save a small sprig for garnishing). Cook and stir for 1 min. Tip in the haricot beans. Crumble in the vegetable stock cube. Pour in 450ml boiling water. Pop the lid back on the pan and simmer the bean broth for 15 mins.

While the broth simmers, heat your grill to high. Line the grill pan or a baking tray with foil. Rub the hake fillets with 1 tsp oil each and season with salt and pepper. Pop them on the grill pan, skin side up, then slide the fish under the grill. Cook for 10–12 mins till the hake is cooked through – the flesh should be white and opaque and flake easily when pressed with a fork.

Taste the bean broth and add a pinch more pepper if you think it needs it. Lift out the thyme sprigs and bay leaf. Ladle the beans, veg and broth into warm shallow bowls. Tip with a hake fillet and sprinkle over a few fresh thyme leaves to serve.