In the bowl of a stand mixer fitted with a dough hook, combine the water, yeast and sugar. Let stand for 5 minutes until the yeast becomes foamy. Stir in 1 cup flour and 1/4 cup olive oil. Let stand for an additional 5 minutes. Add the remaining flour and 1/2 teaspoon kosher salt and mix on medium speed until a sticky but smooth dough forms. Transfer the dough to an oiled bowl and let rest for 1 hour.

Preheat the oven to 400 degrees F.

Arrange the tomatoes, cut side up in a single layer on a parchment lined-sheet pan. Roast for 25-30 minutes until the tomatoes are wrinkled at the edges, but still juicy in the middle.

Increase the oven temperature to 450 degrees F. Oil a 13-inch by 9-inch sheet pan. Stretch the dough to fit the pan. Use your fingers to press dimples all over the dough. Allow the dough to rise slightly, about 20 minutes.

Press tomatoes into the dough. Drizzle with 2 tablespoons olive oil and sprinkle with 1/2 teaspoon flaky sea salt and 1/4 teaspoon black pepper.

Bake for 20-25 minutes until light golden brown. Transfer to a wire rack to cool. Sprinkle with parsley and chives.

Focaccia can be served warm or at room temperature.