Activate the yeast by combining warm water, sugar, and yeast, then let it bloom for 5-10 minutes until foamy.

In a large bowl, mix together the flour and salt, then add the bloomed yeast mixture and 2 tablespoons of olive oil until a shaggy dough forms.

Turn the dough onto a lightly floured surface and knead for 8-10 minutes until it becomes smooth and elastic.

Place the kneaded dough in a lightly greased bowl, cover it, and let it rise in a warm place for 1-1.5 hours, or until it has doubled in size.

Drizzle 2 tablespoons of olive oil into a 9x13 inch baking pan, ensuring the bottom is evenly coated.

Gently press the risen dough into the prepared pan, using your fingertips to create characteristic dimples across the surface; cover and let rise for another 30-45 minutes.

Arrange cherry tomatoes and rosemary sprigs on the focaccia surface to create a festive design, then sprinkle generously with flaky sea salt.

Preheat your oven to 400°F (200°C) and bake the focaccia for 20-25 minutes, or until it is golden brown and cooked through.

Allow the focaccia to cool slightly in the pan before slicing and serving warm as an appetizer.