Preheat the oven to 180°C. Place the couscous, lemon juice and water into a large bowl. Set aside for 5 minutes or until all the liquid is absorbed. Use a fork to separate the grains.
Meanwhile, use a teaspoon to remove the flesh from the eggplant, leaving a 1cm-thick border around the edges. Place the eggplant halves in a baking dish. Finely chop the eggplant flesh and reserve.
Heat half of the olive oil in a large non-stick frying pan over medium-high heat. Add the onion and garlic and cook, stirring, for 2 minutes or until soft.
Add the reserved eggplant flesh and remaining oil and cook, stirring occasionally, for 3 minutes. Add the tomato and cook, stirring, for a further 2 minutes. Add the couscous, currants and mint and stir until well combined. Season with salt and pepper.
Spoon the couscous mixture evenly among the eggplant halves. Brush the edges of the eggplant with some of the extra oil. Sprinkle the feta over the couscous mixture. Drizzle the remaining extra oil over the top.
Bake in oven for 35-40 minutes or until the eggplant is tender. Serve with mixed salad leaves.