Slice the top and bottom off the watermelon so it rests easily on a cutting board. Starting at the top of the watermelon, gently cut down towards the cutting board to remove the peel and white pith.
Slice the watermelon into 1-inch discs, and cut the discs into 1-inch “fries”. This will yield about 4 cups of watermelon fries.
Sprinkle with Tajin, or other chili-lime seasoning. Drizzle with lime juice.
AIR FRY in batches at 400°F for 6-8 minutes, or until the watermelon is hot and slightly browned on the sides.
Scatter on a plate. Top with crumbled feta and chopped cilantro. Serve warm.