Preheat oven to 375 degrees.
Using two baking sheets, place two tortillas side by side on each sheet. With a pastry brush, lightly brush each tortilla with some of the olive oil. Flip tortillas and brush again. Bake 8 to 10 minutes, flipping tortillas and alternating the placement of the baking sheets halfway through the cooking time. (During the first few minutes, use a knife point to pop any air bubbles that might develop.) The tortillas should be golden and crisp when done. (The tortillas may be prepared to this point up to three days in advance. Cool completely, seal in a plastic bag, and refrigerate until ready to use.)
In a large bowl, combine plum tomatoes, black olives, zucchini, red onion slivers, oregano, ground black pepper and olive oil; toss well. Gently fold in crumbled feta cheese and scatter mixture all over the tortillas. Bake 12 minutes, or until the feta is sizzling and the zucchini softened. Alternate the placement of the baking sheets halfway during the cooking time. Cut and serve immediately.