Onion-sauce = the euphemism of "pustule"?

In her annotations Gauger includes a significant amount of biographical information about Grahame and his family and friends, and cites to a greater extent than Lerer authorities on Grahame’s work, such as Peter Green. She also very impressively draws upon archival sources, including the Grahame papers at the Bodleian Library, while Lerer uses only published references. There is remarkably little overlap between their notes: their first common gloss concerns ‘onion-sauce’, Mole’s rejoinder to the rabbits demanding a toll in chapter 1. Lerer defines this as ‘hogwash’, and explains that ‘by the nineteenth century, onion-sauce had come to represent the simplicity of home cooking, in contrast to the fancy cuisine of court or the Continent’ (p. 48). In support, he cites the Oxford English Dictionary, which quotes Dickens’ mention of onion-sauce in Nicholas Nickleby, in association with roast pig. Gauger, for her part, interprets Mole’s words as ‘threatening the rabbits and making a joke at their expense. Onion sauce was always served with baked rabbit’ (p. 4). I would disagree that Mole is making a threat, but rather a rude remark; and Gauger then proceeds to claim that A.A. Milne, like Kenneth Grahame, portrayed rabbits as dimwits, giving as an example Rabbit in The House at Pooh Corner – but Rabbit is by no means dim, even if he isn’t always as clever as he thinks.