Lightly coat a quarter sheet pan with nonstick spray. Brush 2 tablespoons (25g) olive oil over sheet.
In a liquid measuring cup, combine 1 ½ cups (340g) water, 2 teaspoons (17g) honey and 1 tablespoon (10g) yeast; let sit until foamy, about 5 minutes. Stir in remaining 3 tablespoons olive oil.
Add 2⅔ cup (345g) bread flour, ⅔ cup (75g) rye flour, 4 teaspoons (8g) za’atar and 1½ teaspoons kosher salt to bowl of a stand mixer fitted with paddle attachment; mix to combine. With mixer on low speed, add water-yeast mixture. Increase speed to medium-high and mix until smooth and sticky, 80 seconds.
Scoop sticky batter into prepared pan, and, using oiled hands, spread into an even layer and into edges. Cover with a clean kitchen towel and let rise at room temperature for 60 minutes — it should be quite puffy, but not fragile-looking.
Meanwhile, heat oven 375°F (190ºC) with rack set in middle position.
Drizzle dough lightly with olive oil then oil your hands, using finger tips, gently poke dough all over.
Drizzle a bit more olive oil over top then sprinkle 2 tablespoons sesame seeds, ½ teaspoon sumac and ½ teaspoons flaky sea salt over top.
Bake bread until golden brown on top, 25—32 minutes.
Immediately flip bread out onto a wire rack to cool. Cool completely before cutting and serving.