Step 1: Preheat your oven to 400°F (200°C). Lightly grease a 9×13 inch baking pan (or a similar size round pan) with olive oil.
Step 2: In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, and 1 teaspoon of fine sea salt. Make sure there are no lumps.
Step 3: Pour in the sparkling water and 1/4 cup of olive oil. Stir with a spatula or wooden spoon until just combined. The dough will be shaggy and sticky. Do not overmix; a few lumps are okay. This ensures your Quick Yeast-Free Sparkling Water Focaccia stays tender.
Step 4: Transfer the dough to the prepared baking pan. Using your olive oil-greased hands, gently spread the dough evenly across the bottom of the pan. It will be a bit sticky, so keep your hands oiled.
Step 5: Drizzle the remaining 2 tablespoons of olive oil generously over the top of the dough. Use your fingertips to create deep dimples all over the surface of the focaccia, pressing all the way down to the bottom of the pan. This is crucial for that authentic focaccia texture and for the oil and toppings to settle.
Step 6: Sprinkle the chopped fresh rosemary and a generous pinch of flaky sea salt over the dimpled dough. If using, press in any optional toppings like halved cherry tomatoes or sliced olives. This elevates the flavor of your Quick Yeast-Free Sparkling Water Focaccia.
Step 7: Bake for 18-22 minutes, or until the focaccia is golden brown on top and cooked through. The internal temperature should reach about 200°F (93°C).
Step 8: Remove the pan from the oven and let the focaccia cool slightly in the pan for 5-10 minutes before transferring it to a wire rack. This helps prevent it from getting soggy. Slice and serve your delicious Quick Yeast-Free Sparkling Water Focaccia warm.