In a medium sized bowl, whisk together all the ingredients for the sauce. Set aside.
For the grill
Cut off dark green parts of leeks and split white and light green part in half lengthwise. Rise to remove any grit, then set on a baking dish cut side down.
Trim stem off eggplant and slice lengthwise into ½ - ¾ inch thick pieces. Place on baking dish with leeks.
Drizzle vegetables generously with canola oil, salt, and pepper.
Prepare grill for medium-high heat. Using a brush or a paper towel, gently grease the grill plates. Place eggplant pieces and leeks (cut side down) onto the grill, working in batches if needed, and cook for about 5 minutes per side, until vegetables are slightly charred and have distinct grill marks. Transfer back to baking dish.
Assemble: Coarsely chop leeks and eggplant and transfer to bowl. Give the sauce another whisk to bring it back together, then pour it over the vegetables. Gently toss to coat, taste, and adjust salt and lime juice if needed. Transfer vegetables to serving dish and top with fish. Sprinkle with cilantro and more lime juice if needed and serve immediately.