Preheat oven to 400°F
Labnah: in a bowl add yogurt and salt, stir to combine. Place two layers of cheesecloth over a colander with at least an inch of overhang on sides and place a bowl under it.
Add yogurt and salt mixture to cheesecloth-lined colander and pull cheesecloth back over the top on all sides, covering the mixture. Place another bowl on top of this mixture and add a can or two to weigh the bowl down and gently drain the liquid. Cover with plastic and place in cooler for about 24 hours (at least 12 hours).
When labneh is finished draining, discard the liquid in the bowl and remove the cheesecloth. Transfer to a bowl and add 1Tbsp. of lemon zest and 2 cloves of roasted garlic, whisk until thoroughly combined and whipped. Set aside in cooler, covered.
In a bowl, lightly drizzle 2 Tbsp. of olive oil on sliced eggplant and season with salt. Place eggplant slices in a single layer on a sheet tray with parchment and place in oven for 10 minutes, until golden brown. Remove from oven and set aside to cool.
Tartine: toast sliced bread to order (2 pieces per order) in a pan with 2-3 Tbsp. of olive oil, until both sides are golden brown and crisp.
Spread about 2 Tbsp. of Labnah on each piece of bread evenly, then top with roasted eggplant slices, sprinkle with 1-2 tsp. ofza’atar spices. Then place cucumbers and radishes, shingled neatly, on top. Finish with freshly torn mint, a sprinkle of sea salt flakes, and a drizzle of olive oil.