Preheat oven to 350 degrees F. Drizzle the slices of bread with olive oil and bake until golden, about 10 minutes.
Spread the smashed avocado or avocado hummus across the toasted bread. Top with sliced avocado, tomatoes, a sprinkle of sea salt, and lemon zest. Cut each tartine into triangles and drizzle with more Greek olive oil. Enjoy!