Combine the tomatoes, garlic, oregano, and parsley in a large bowl and season with salt and pepper. Let sit at room temperature while you prepare the eggplant or for up to 2 hours.
Combine the ricotta and lemon zest in a small bowl and season with salt and pepper. Cover and refrigerate while you prepare the eggplant or for up to 2 hours.
Heat a grill to high or a grill pan over high heat.
Brush the eggplant on both sides with the canola oil and season with salt and pepper. Grill the eggplant, cut-side down, until golden brown and caramelized, about 4 minutes. Flip the eggplant and grill until the bottom is golden brown and the eggplant is tender, about 3 minutes more.
Transfer the eggplant to a platter, cut-side up, and top each half with a large dollop of the ricotta. Spoon the tomatoes over the top and serve.
In the summer, you can substitute 3 ripe large beefsteak tomatoes, halved, seeded, and diced and 12 fresh basil leaves, thinly sliced for the cherry tomatoes and oregano.