```python
from fastapi import FastAPI
from fastapi.responses import JSONResponse
import asyncio
from concurrent.futures import ThreadPoolExecutor

import helpers  # the provided API

app = FastAPI()

# Reusable thread pool for running blocking calls off the event loop
_executor = ThreadPoolExecutor(max_workers=8)


def _submit(order: dict) -> dict:
    """Helper that runs the synchronous processing in a thread."""
    return helpers.process_order(order)


@app.post("/orders")
async def create_order(order: dict):
    """Process an incoming order without blocking the event loop."""
    loop = asyncio.get_event_loop()
    try:
        processed = await loop.run_in_executor(_executor, _submit, order)
    except Exception as exc:
        return JSONResponse(
            {"detail": f"Order processing failed: {exc}"},
            status_code=500,
        )
    return JSONResponse(processed, status_code=201)
```