Preheat the oven to 200 degrees C. Cut the eggplants lengthwise into slices about 1cm thick. Place on a non-stick baking tray, brush on both sides with 1 tablespoon of the olive oil, salt sparingly and bake for 8–10 minutes on each side until golden and tender. Set aside.
Cut the avocado in half, remove the stone, peel off the skin and dice the flesh. Sprinkle with 1 tablespoon of the lemon juice and a little salt.
Bring a large saucepan of lightly salted water to the boil. Add the pasta and cook for 10 minutes, or according to the packet instructions, until al dente.
Dice the eggplant. Skim off and reserve 1 tablespoon of the pasta cooking water, then drain the pasta. Tip the pasta into a large deep bowl with the reserved water. Add the eggplant, avocado, capsicum and feta. Gently toss to mix. Pour over the remaining olive oil and lemon juice. Season with pepper and toss once more. Serve warm or at room temperature.