There could be many causes for the swelling. Presuming it's the normal inflammatory reaction post an extraction, you could have anything soft at room temperature.
Precautions :
-Nothing hot or spicy to be consumed
-Gargle after meals to ensure the area is free from food debris accumulation
-Do not brush vigorously in the extraction area
-try and keep your tongue from touching the area unnecessarily
Next Steps
Follow up with the dentist who has extracted the tooth to evaluate the wound