minecraft-assets/data/minecraft/recipes/oak_sign.json

{
  "type": "minecraft:crafting_shaped",
  "pattern": [
    "###",
    "###",
    " X "
  ],
  "key": {
    "#": {
      "item": "minecraft:oak_planks"
    },
    "X": {
      "item": "minecraft:stick"
    }
  },
  "result": {
    "item": "minecraft:oak_sign",
    "count": 3
  }
}