In a mixing bowl, combine warm water and yeast. Let it sit for 5 minutes until frothy.

Add flour, salt, and olive oil to the yeast mixture. Mix until a dough forms.

Knead the dough on a floured surface for about 10 minutes until smooth.

Place the dough in a greased bowl, cover, and let it rise in a warm place for 1 hour or until doubled in size.

Preheat the oven to 425°F (220°C).

Once risen, punch down the dough and spread it onto a greased baking sheet. Dimple the surface with your fingers.

Drizzle with olive oil and sprinkle with salt. Bake for 20 minutes until golden brown.

Once the focaccia is cooled, slice it horizontally.

Spread pesto sauce on the bottom half of the focaccia.

Layer with mozzarella slices, tomatoes, and basil leaves.

Top with the other half of the focaccia and press gently.

Cut into individual sandwiches and serve.