01 - 
                Mix mayonnaise, ketchup, and garlic powder. Refrigerate until serving.
              
              
              
                02 - 
                Peel plantains and cut into 1 1/2-inch chunks. Soak in salted water for 20 minutes.
              
              
              
                03 - 
                Set air fryer to 350°F (175°C).
              
              
              
                04 - 
                Dry plantains, toss with 1 tablespoon oil. Air fry 3-6 minutes per side until soft.
              
              
              
                05 - 
                Flatten each piece to 1/4-inch thick using a tostonera or mug.
              
              
              
                06 - 
                Increase air fryer to 400°F (200°C). Brush tostones with oil, fry 3 minutes, flip, oil again, fry 4 minutes.
              
              
              
                07 - 
                Sprinkle tostones with coarse salt. Serve hot with mayo-ketchup dip.