How long do you cook a 3.5 lb roast beef in bag?

I cannot give you a specific cooking time for a 3.5 lb roast beef in a bag. Here's why:

* Cooking Time Varies: Factors like the cut of beef, desired level of doneness, and your oven's temperature all affect cooking time.

* Bag Type: Different bag types (nylon, oven-safe plastic, etc.) have different heat tolerances.

* Recipe and Instructions: Each recipe and cooking method will have its own set of instructions.

To Determine the Right Time:

1. Consult a Reliable Recipe: Find a recipe for roast beef in a bag that matches your desired cut and doneness. It will provide detailed instructions, including cooking times.

2. Use a Meat Thermometer: This is the most accurate way to determine doneness. Check the internal temperature of the roast to ensure it's cooked to your liking.

3. Adjust Cooking Time: If the roast isn't cooked through after the recipe's suggested time, continue cooking in 15-minute intervals until it reaches the desired temperature.

General Tips:

* Start Low: For most roast beef, start cooking at a lower temperature (around 325 degrees F) to ensure even cooking.

* Rest After Cooking: Allow the roast to rest for 10-15 minutes after cooking before carving. This allows the juices to redistribute.

Enjoy your delicious roast beef!