ETA: My mistake; what it really is is an old-run that asks the musical question "Elly mistakenly believes she can hide her failings as a housewife from John."
Panel 1: We begin with a freaked-out Elly carrying a bowl of dough.
Panel 2: Said bowl of dough makes a FLOOP noise as she dumps it in the garbage.
Panel 3: We shift our attention to the kitchen; there's an open bag of flour and mixing bowl on the counter where Elly's sitting. With one hand grasping the phone handset and a measuring cup in the other, a panicked Elly says in Lynnglish "Annie? You know that twenty four loaves of bread I was baking for your bazaar?"
Panel 4: Having piqued her friend's curiosity, she explains that she forgot to put salt in the batter, thus "ruining" it.
Panel 5: In response to Annie's question about what she did to it, she angrily explains that she had no choice but to get rid of it. It's at this point she and most of us part company mentally; nobody I know of would have cared if the bread had no salt in it. What's more, almost everyone I know would have added the salt afterward and given the stuff a little more work instead of wasting it like an imbecile.
Panel 6: She's simply glad that she did so in a manner that John would never discover. If he did, she'd never hear the end of it. Too bad she doesn't know why they add salt to bread dough. Without anything to kill the yeast, it's going to keep rising if left uncooked.
Panel 7: Thus it is that a confused John stares goggle-eyed at the fruit of Elly's testy ineptitude, haste, wastefulness and idiocy as Mike explains to him that the big blob of dough has been growing all afternoon. [not_bridgett put it best when she asked if a festering lump of garbage, the result of waste & stupidity, was a good symbol of this latest arc.]
Summary: Remember when Elly was giving him the iceberg treatment in bed for no reason we could determine and got even more pissed off because he pointed out how gutless she was? Maybe he made the foolish mistake of pointing out that the dough wasn't ruined after all and all she needed to do was work on it a bit more like his mom would have.