```python
from fastapi import FastAPI, Body, HTTPException

import helpers

app = FastAPI()


@app.post("/orders", status_code=201)
async def create_order(payload: dict = Body(...)):
    item_name = payload.get("item")
    if not item_name:
        raise HTTPException(status_code=400, detail="Missing 'item' field")
    await helpers.aappend_audit_line(f"order:{item_name}")
    return {"status": "created"}
```