Combine aubergine and 2 tablespoons salt in a large bowl with water to cover. Place a plate on top of the aubergine to weigh it down and keep it covered in water for about 30 minutes. Drain and rinse aubergine in cool water. Pat dry and cut into cubes.
Heat oil in a pan over medium-high heat. Saute aubergine until golden brown, about 6 minutes. Drain on kitchen paper.
Combine tomato passata, 1 teaspoon rock salt, garlic and basil in a saucepan over medium-low heat. Simmer, stirring occasionally, until sauce flavours combine, about 5 minutes.
Bring a large pot of lightly salted water to the boil; add penne and cook, stirring occasionally, until tender yet firm to the bite, about 11 minutes. Drain and toss with the tomato-basil sauce; divide into 4 serving bowls. Top with aubergine. Sprinkle 1/4 the ricotta and 1/4 the diced pepper over each bowl.