How to Make It
Preheat oven to 400°F. Remove stem from wax pepper. Rub pepper with 1/8 teaspoon oil; place on a small baking sheet or piece of aluminum foil. Roast at 400°F until slightly blistered, 10 to 12 minutes. Let pepper stand until cool enough to handle; rub off and discard skin.
Combine juice and garlic in a bowl; let stand 5 minutes. Finely chop pepper; add to garlic mixture. Stir in yogurt, 3 tablespoons water, mint, and 3/4 teaspoon oil.
Reduce oven temperature to 350°F. Split each pita into 2 rounds. Cut pita rounds into wedges, and place in a bowl. Drizzle with 2 tablespoons oil; toss gently to coat. Place in an even layer on 2 baking sheets. Bake at 350°F until browned and crisp, about 10 to 12 minutes.
Heat 2 teaspoons oil in a skillet over medium. Add onion; cook until translucent, about 5 minutes. Add corn; cook, stirring often, until tender, about 4 minutes. Stir in 1 teaspoon cumin and black pepper.
Arrange pita chips in an even layer on a platter (they can overlap). Spoon corn mixture evenly over chips. Toss lettuce and tomato with remaining 1/8 teaspoon oil and remaining 1/2 teaspoon cumin; sprinkle over nachos. Drizzle yogurt mixture over nachos, then top with crab and avocado. Sprinkle with sumac and salt.