1 cup water
1 tsp active yeast
1 Tbsp coarse salt, divided
3 Tbsp sugar, divided
1/4 cup olive oil, divided, plus additional for greasing the bowl and handling the dough
2 ¼ cups (10 ounces) bread flour
heaping cup halved and seeded concord grapes (warning: seeding the grapes may take longer than you think)
2 tsp fresh rosemary needles
Combine the water and yeast in a bowl, and let sit for a minute or two to allow the yeast to soften and bloom. Add 1 teaspoon of the salt, 1 tablespoon of the sugar, 2 tablespoons of the oil, and the flour. Mix with a large spoon until fully blended, then cover and let sit for 5 minutes to fully hydrate. Mix for an additional minute or two, until the dough becomes smooth. Grease another bowl with a bit of oil, and, using a spatula, transfer the dough into the bowl. Cover and let rest for 10 minutes.
After the dough has rested, using wet or oiled hands, reach into the bowl under one end of the dough, and pull it gently to fold the dough in half. repeat with the other three sides of the dough, then flip the whole doughball over. Let rest 10 minutes, then repeat 2-3 more times. After the last folding, cover the bowl, and refrigerate overnight, or up to three days. These folds may seem a bit fussy, but achieve the dual purpose of folding in some air holes into the dough, and firming it up without using additional flour.
About 1 1/2 - 2 hours before you’d like to bake (depending on how warm your kitchen is), take the dough out of the refrigerator, and allow to come to room temperature for ~45 minutes to take the chill off. Line two baking sheets with parchment paper, or brush them heavily with olive oil. Gently divide the dough into two balls (they might be a bit more like blobs then balls), and place them on the prepared sheets. Let sit 10 minutes to relax, then, with oiled or wet hands, use your fingertips to sort of pat-and-push the dough out into 9” circles from the inside out, dimpling them without totally compressing them (if they resist, you can pat them out a little, let the dough rest ~5-10 minutes, then pat them out a little more and repeat as needed -- it’s important you press the dough out to out least this diameter, otherwise it will be too thick to cook properly). Let rise for 45 minutes to an hour (depending on the heat of your kitchen). While the dough is rising, preheat the oven to 500.
When the dough has risen, brush the focaccia with the remaining oil. Sprinkle them with the grapes, rosemary, and remaining 2 tablespoons sugar and 2 teaspoons coarse salt. (that's 1 Tbsp/tsp per focaccia). Place the trays in the oven, then turn down the heat to 450. Bake for ~20 minutes, until the focaccia has cooked to a golden brown (it may seem a little underdone in some parts around the grape divots, but as long as the non-grape parts are browned it will be fine). Let cool slightly, then serve warm or at room temperature (ideally within a few hours for optimum deliciousness).