minecraft-assets/data/minecraft/recipe/fire_charge.json

{
  "type": "minecraft:crafting_shapeless",
  "category": "misc",
  "ingredients": [
    "minecraft:gunpowder",
    "minecraft:blaze_powder",
    [
      "minecraft:coal",
      "minecraft:charcoal"
    ]
  ],
  "result": {
    "count": 3,
    "id": "minecraft:fire_charge"
  }
}