In a mixing bowl, combine warm water, yeast, and sugar. Let it sit for about 5 minutes until it starts to foam.
In a large mixing bowl, combine flour and salt. Pour in the yeast mixture and 1/4 cup olive oil, and mix until a dough forms.
Knead the dough on a floured surface for about 10 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a damp cloth, and let it rise in a warm place for about 1 hour or until it doubles in size.
Preheat the oven to 425°F (220°C).
Once the dough has risen, punch it down and transfer it to a baking sheet lined with parchment paper. Stretch it out to fit the sheet, creating dimples with your fingers.
Drizzle olive oil over the surface of the dough and sprinkle with oregano, garlic powder, salt, and the halved cherry tomatoes.
Bake for about 20-25 minutes until golden brown. Remove from the oven and let it cool slightly.
Cut the focaccia in half horizontally and layer mozzarella cheese and fresh basil leaves on the bottom half. Season with salt and pepper.
Place the top half back on and press gently. Cut into individual sandwiches.
Notes
Serve the focaccia sandwiches on a wooden board, sliced into portions, garnished with extra basil leaves and a small bowl of olive oil for dipping.