In a large bowl, combine the warm water, yeast, salt, olive oil, and flour. Mix with a spoon or your hands until a sticky dough forms.
Cover the bowl and let the dough rise at room temperature for 2 hours.
Wet your hands with a little water and gently stretch and fold the dough 3–4 times. Cover again and refrigerate for 4–24 hours.
Remove the dough from the refrigerator and gently transfer it to a greased 9x13-inch baking pan. Carefully spread it to fit the pan without deflating it.
Cover and let the dough rise for 1 hour. If it hasn't become light and puffy, let it rise for another hour.
Preheat your oven to 450°F (230°C).
Drizzle the top generously with olive oil. Add the Italian seasoning, cherry tomatoes, and olives. Using your fingertips, gently press dimples all over the dough.
Bake for 20–25 minutes, or until the focaccia is beautifully golden brown.
Let it cool for a few minutes, then enjoy it warm, or allow it to cool completely before slicing and serving.