How to Make It
Preheat broiler with rack 6 inches from heat. Place jalapeño on a baking sheet and broil until charred in spots, 5 to 8 minutes. Let cool for 5 minutes. Finely chop and transfer to a small bowl; stir in mayonnaise and ¼ teaspoon salt. Set aside.
Heat oil in a medium skillet over medium-high. Add 1 tortilla; cook, flipping once and pressing down with a spatula for even coloring, until golden, about 1 minute per side. Transfer to a baking sheet lined with paper towels. Repeat with remaining 3 tortillas. (Reduce heat as needed if tortillas get too dark around edges.) Season fried tortillas with ¼ teaspoon salt.
Stir crabmeat, celery, shallot, lime juice, pepper, and remaining ½ teaspoon salt in a bowl until combined. Spread jalapeño mayonnaise over tortillas and top with crabmeat mixture. Top with radishes, celery leaves, and hot sauce (if using).
After tasting the celery leaves in this easy meal, you'll never throw them away again.