Preheat oven to 400ºF.
Slice eggplant into 1-inch cubes and lay in a single layer on a baking sheet. Sprinkle with 1 teaspoon sea salt and toss. Let sit for 20 minutes, then squeeze the eggplant with paper towels to remove excess water.
Add chickpeas to the baking sheet, drizzle with olive oil, and sprinkle with za'atar, coriander, and cumin. Toss to coat thoroughly and return to a single layer. Roast for about 30 minutes, stirring halfway through, until eggplant is tender and browning, and chickpeas are beginning to get crisp on the outside.
In a measuring cup or bowl, whisk together tahini, water, lemon juice, garlic, and 1/2 teaspoon salt until it turns pale and homogenizes into a dressing.
Cut heirloom tomatoes into medium-thick slices and layer five or six slices on a single plate, per serving. Drizzle with olive oil and red wine vinegar, then sprinkle with sea salt and chopped basil. Top with a hearty handful or two of roasted chickpeas and eggplant, and drizzle with tahini dressing. Finish with a fragrant handful of basil.