In a large mixing bowl, combine the chopped cucumbers, halved cherry tomatoes, sliced green olives, finely chopped shallot, and roughly chopped parsley. Toss until well mixed and set aside.

In a small bowl, whisk together the olive oil, fresh lemon juice, salt, and pepper. Pour it over the salad and toss again to coat.

Heat a non-stick skillet over medium heat and lightly toast the corn tortillas for 1-2 minutes on each side until golden brown and crispy.

Spread approximately two tablespoons of hummus on each tortilla, then heap about a quarter cup of the prepared salad on each.

Drizzle tahini over each tostada, adding water if needed to achieve a pourable consistency.

Serve immediately for the best crunch, or store the salad and hummus separately if preparing in advance.