Punctuating dialogue interrupted by speaker?

Question

When a speaker briefly interrupts their own dialogue, then resumes in the same paragraph, how do you punctuate the interruption?

I know that, when it doesn't halt speech (i.e. dashes outside quotes), you use lower case and no full stop. Like so:

"Well I heard"—her voice dropped to a whisper—"that she stole it."

But what if speech is halted (i.e. dashes inside quotes)?

Which of these is right?:

"It's good, but—" He took another bite. "—it could use more salt."

"It's good, but—" he took another bite "—it could use more salt."

[Please no examples where the interruption is by another person, or there's a paragraph break. That's a slightly different situation (with lots of answers already) and not helpful.]

[ETA: It's been pointed out that "it could use more salt" could be considered a separate sentence, thus avoiding the issue. As I'm specifically looking for the right punctuation (capital and full stop? yes/no?) for an interrupted full sentence (and not just this sentence in particular), please pretend that it can't.]

Answer 1

Really good question. Personally, I haven't observed em dashes used for this particular case. Em dashes tend to indicate that something has happened suddenly, perhaps interruption by a different actor (as you mentioned), or perhaps some other reflexive change (how I'm interpreting your whisper example).

Your specific example in question involves a case where the subject took time for a deliberate action in the middle of a thought. Due to the lack of suddenness, I'd encourage considering an ellipsis for this. It could be implemented as either a trailing off of one sentence and the creation of a second sentence, or as one continued sentence, depending on the forcefulness you're aiming for. (Two separate sentences is interpreted as more forceful.)

"It's good, but…” He took another bite. “…it could use more salt."

"It's good, but…” He took another bite. "It could use more salt."

If you want to stick with em dashes (totally reasonable), I would give preference to the first option you provided. My rationale is that the text "he took another bite" needs to be anchored with some sort of punctuation, and in your second option it has none; it's totally free-floating.

Answer 2

The first dash shows that the speaker was cut off (by himself in this case). The second dash does nothing.

"It's good, but⸺." He took another bite. "It could use more salt."

The grammar makes it fairly clear that the dialogue is cut off, so you could also avoid the punctuation predicament altogether.

"It's good, but," he said, stopping to take another bite. "It could use more salt."

"It's good, but," he took another bite, "it could use more salt."

Answer 3

"He took another bite", within another sentence, is complete in itself. Hence start in upper case and end with a period.

"It’s good, but [He took another bite.] it could use more salt."

Another option could be: "It's good, but — he took another bite — it could use more salt."

Quote-marks within another quote-marks makes it clumsy. In similar situations, use "...." for the parent sentence, and '....' for the sentence within, like "It's good, but — 'he took another bite' — it could use more salt." Again the whole structure looks clumsy.

To show it a part of a bigger sentence, an ellipsis with no caps and/or period, may be considered too. https://www.grammarbook.com/punctuation/ellipses.asp

It’s good, but [...he took another bite] it could use more salt.