Peel and finely chop the onion. Rinse, trim and chop the celery. Rinse the pepper and halve it. Scoop out the seeds and white bits. Roughly chop it. Peel and crush or grate the garlic. Rinse and pat dry the thyme. Pick the leaves from the stalks.
Warm a splash of olive oil in a large pan. Add the onion, celery and pepper. Fry over a medium heat for 6-8 mins till soft but not coloured. Stir every so often. Fill the kettle and boil it.
Add the garlic, a pinch of the cayenne pepper, three-quarters of the thyme and the rice. Cook and stir for 1-2 mins. Add the tomatoes. Cook and stir for 5 mins till most of the liquid has been absorbed.
Crumble the stock cube into 300ml hot water from the kettle. Stir till dissolved. Pour into the rice. Cover. Turn the heat down. Simmer over a low heat for 10 mins. Stir every so often to stop the rice sticking.
Rinse and trim the aubergine. Cut into slices around 2 cm thick. Sprinkle with a pinch of two of the Cajun spice mix.
Drain and rinse the kidney beans. Add them to the rice with 150ml more hot water from the kettle. Cook for 10 mins. Stir every so often till the rice is tender. Taste and season.
Warm a splash of olive oil in a frying or griddle pan. Fry the aubergine steaks over a low to medium heat for 4-5 mins on each side till golden brown and tender. Drain the aubergine on kitchen paper.
Serve the red rice and beans topped with the aubergine steaks. Scatter over the rest of the thyme.