First, it should be using "a" microwave.
In both cases, your phrases are participial phrases acting as adverbs that modify the main verbs.
Student or Learner
Please help me to identify the type of this clause
I prefer to stay at home watching TV.
I prepared meal using microwave.
Is watching TV , using microwave considered as a Noun, gerund or participle phrase?
Thank you very much.
The original should be "I prepared a/the meal ...".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
My preference is watching TV at home.
I prepared the meal by using a microwave.
Are they gerunds now?