1. Back home, I went online and found the recipe.
2. When I was back home. I went online and found the recipe.
3. After I was back home. I went online and found the recipe.
4. (Being) back home. I went online and found the recipe.
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Does #1 come from #2 or #3?
Is 'being' deleted before 'Back'?
If 2 and 3 have commas instead of periods after "home," they would be the origins of #1, yes. An alternative for #1 is "At home, I went online ... "
#4 would not be used with the word "Being" but if that word were removed, the sentence would be fine.
1. Back home, I went online and found the recipe.
2. When I was back home, I went online and found the recipe.
3. After I was back home, I went online and found the recipe.
4. (Being) back home, I went online and found the recipe.
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Does #1 come from #2 or #3?
Is 'being' deleted before 'Back'?
Does #1 come from #2 or #3? Yes -- from either or both.
Is 'being' deleted before 'Back'? Yes, it needs to be deleted.
To answer your questions:
1. The first sentence, "Back home, I went online and found the recipe," can come from both #2 and #3. Both of these sentences convey the same meaning and can result in the same wording.
2. Yes, in sentence #4, "Being" is typically deleted before "back." This deletion is quite common in informal speech and writing. However, it is important to note that the inclusion or omission of "being" can vary depending on the context and personal preference.