Step 1Combine 1 tablespoon lemon juice, 2 teaspoons olive oil and half of the garlic in a shallow ceramic dish. Add prawns and stir to coat. Cover and place in fridge for 30 minutes.
Step 2Heat remaining oil in a large, deep non-stick frying pan over medium heat. Sauté onion for 5 minutes, or until softened. Add lemon zest and remaining garlic and cook, stirring, for 1 minute or until fragrant. Add capsicum and cook, stirring, for 2 minutes. Add black beans and kale and cook, stirring, until kale is wilted.
Step 3Boil the stock in a saucepan and add the couscous; stir. Cover, remove from heat and set aside to steam for 5 minutes. Fluff grains with a fork, stir through the remaining lemon juice and season with pepper.
Step 4Meanwhile, heat a large char-grill pan over a high heat. Grill the prawns for 2 minutes each side, or until lightly charred and cooked through.
Step 5Divide couscous, beans and vegies between 4 serving plates and top with the prawns.