Peel the onions, halve and deseed the pepper, then finely chop both. Halve, deseed and finely chop the chilli. Pick the basil leaves and finely chop the stalks.
Heat 1 teaspoon of olive oil in a large, deep frying pan over a medium heat, add the basil stalks and chopped veg and cook gently for 5 minutes, or until the vegetables are soft, stirring occasionally.
Pound the fennel seeds in a pestle and mortar or bash with the base of a pan until fine, then add to the pan with the bay leaf.
Place the couscous into a bowl with a pinch of salt and pour over 300ml of boiling water.
Halve the cherry tomatoes and add to the pan with the softened vegetables. Season, then stir together and shake the pan so the veg is in one layer.
Drizzle the salmon with extra virgin olive oil and season lightly with sea salt and black pepper.
Tip the couscous over the vegetables and smooth out. Carefully pour over another 300ml of boiling water, then place the salmon fillets on top of the couscous, skin-side down.
Finely grate over the lemon zest and squeeze over the juice.
Cover the pan with a lid or tin foil, and cook on a low heat for 12 to 15 minutes, or until the couscous has fluffed up and the salmon is just cooked.
Top each salmon fillet with 1 tablespoon of yoghurt, drizzle with extra virgin olive oil and season with salt and pepper.
Roughly tear and scatter over the basil leaves, then place the pan in the middle of the table and enjoy.