Tip the couscous into a large heatproof bowl. Pour in 150 ml boiling water. Cover with a plate or cling film and set aside to let the water soak in.
If you have a gas hob, set a medium burner to a medium heat. Lay the whole aubergine directly on the flame and char it for 10 mins, turning it every so often using tongs, till it's blackened all over and
soft. If you don’t have a gas hob, heat your grill to high. Lay the whole aubergine on a rack in the grill pan or on a baking tray and grill for 10 mins, turning every so often. Set aside on a plate to cool.
Peel and grate or crush the garlic. Finely grate the zest from the lemon. Put the garlic and zest into a large bowl. Squeeze in the juice from the lemon. Add the tahini with a pinch of salt and pepper. Whisk together with 2 tbsp water and 1 tbsp olive oil to make a smooth paste.
Peel the blackened skin off the aubergine (mind your fingers if the aubergine is still hot). Add the flesh to the bowl with the tahini. Use a fork to mash everything together. Taste and add more salt and pepper if it needs it.
Trim the roots and ends off the salad onions and finely slice them. Halve the cucumber and dice one half (see our tip for what to do with the other half). Fluff the couscous with a fork, then stir in the
spring onion and cucumber with a pinch of salt and pepper.
Separate the lettuce leaves and finely shred them. Toss with ½ tbsp olive oil and some salt and pepper.
Put a griddle or frying pan over a high heat to warm up. Rub ½ tbsp olive oil into the steaks and season with salt and pepper. When the pan is really hot, fry them for 1-3 mins on each side,
depending on how well done you like your steak. Serve with the couscous, lettuce and spoonfuls of smokey baba ganoush.