Heat 1 tablespoon of the oil in a frying pan, add the soya beans, season with a little salt and fry for 2-3 minutes or until they begin to soften.
Transfer to a bowl and allow to cool, add the red onion and black eye beans, cover and refrigerate for 1 hour or until chilled.
To prepare the tuna, pour the Thai 7 spice blend onto a plate and evenly coat each of the tuna steaks.
Heat a frying pan over a high heat until scorching hot. Add the oil and fry the tuna steaks in the pan (no more than 2 at a time) for around 1 minute on each side.
The tuna should be seared on the outside but still pink in the centre. Remove from the pan and allow to rest before slicing.
When ready to serve, stir the soy sauce, lime juice and crushed chillies through the bean mix and spoon onto a plate. Top with the sliced tuna.