Preheat oven to 375°.
To prepare chips, coat rough side of each pita half with cooking spray; sprinkle pita halves evenly with cumin seeds, oregano, and 1/2 teaspoon kosher salt. Cut each pita half into 8 wedges; arrange wedges in a single layer on baking sheets. Bake at 375° for 15 minutes or until golden brown.
To prepare dip, discard husks and stems from tomatillos. Place tomatillos in a small saucepan; cover with water. Bring to a boil; cook 5 minutes or until tender. Cool to room temperature. Place tomatillos, onion, cilantro, jalapeño, and 1/2 teaspoon salt in a blender or food processor, and process until smooth. Add sour cream and avocado; process until smooth. Serve with chips.