Ah, the ol' mock meat "gotcha" question. But let's give her some credit. My mother, whose diet is probably 80% plant-based, was genuinely curious, so I tried to offer a genuine response.
To me, it boils down to this: what's a hot dog have to do with Nonhuman Animals anymore than a veggie dog? Both of them are just protein links heavily seasoned and artificially shaped for palate pleasure. Neither of them look, smell, or taste anything like a pig's corpse.
Theoretically, I see mock meats as culturally relevant in the way that pornography is to women. The mock meat industry and the pornography industry exist as symbolic representations of violence against the vulnerable (with the exception being that pornography entails the physical harm of actual women in its production process). I think we are right to be critical of mock meat as a cultural matter.
However, based on my observations in the vegan community over the years, mock meats do not seem to take up a huge part of the diet, and most people who stay vegan long enough transition off of them. Mock meats, while convenient, are frequently expensive and unhealthy. For those living in food deserts and underserved communities, they're also difficult to source for most.
I also project that, in another few decades, mock meats probably won't even be associated with the Nonhuman Animals they are supposed to be mimicking. The objectification and commodification process is a sophisticated one that easily removes the "person" from the product.
Allow me to explain what I mean by this. For most consumers who have not had their consciousness raised (which is true of most nonvegans), Nonhuman Animal products are already shaped and flavored in a way that removes them from the being they once were, and few are consciously aware of this absent referent (to use the language of Carol J. Adams). Sure, if you think about it, a hamburger or milkshake was once part of a living breathing person. But marketing works hard to eliminate that guilt-inducing, not so pleasurable reminder. Few people really, truly do think about it. Food consumption is socially constructed behavior--the system is structured in a way to encourage mindless eating and eliminate critical thinking and personal agency. If this happens so seamlessly for actual Nonhuman Animal products, then I predict that plant-based foods (those that are mocking animal-based foods, which are themselves pretending not to be animal-based) will probably absorb fully into unconscious consumption patterns.
Mock meats, just like "real" meats, are shaped, flavored, and textured to encourage consumption. They no more resemble Nonhuman Animals than potato chips resemble potatoes, or fruit punch resembles fresh fruit. It's processed junk that appeals to the base nature of human desire: smells and tastes of fat, sugar, and carbohydrates.
I asked a colleague of mine for their thoughts, "I didn't go vegan because I reject certain shapes or flavors. And even as a nonvegan, I didn't sit there and relish the killing. I relished the flavors."
And then there is my partner, also vegan for reasons of ethical concern, who just cannot bring himself to eat vegetables. Where would he be without smoked tofu? Would he live? Sure. Is it worth arguing over because it might be shaped and flavored like animal corpses sometimes are? I don't think so.
For that matter, where would Asian culture be without smoked tofu? Buddhists have been creating soy-based (and wheat-based) protein products for centuries. It is a practice also based in ethics, and mock "meats" are understood to be foundational to living non-violently. Western markets may have corporatized plant-based proteins (and The Vegan Society actually encourages the development of animal-free alternatives),1 but, long rooted in Asian traditions, their history is much older than that. To make sweeping claims about the inherent unethical nature of mock meats is to run the risk of ethnocentrism.
So to answer your question, Mom, if we're talking about mock meats that strongly resemble the corpses of other animals, okay, this is problematic in the context of a deeply speciesist society. But if we are talking about chunks of protein that are shaped and flavored and don't resemble anyone, then these are foods I'm not especially worried about. I have more important concerns on my anti-speciesist agenda.
1. The definition of veganism according to The Vegan Society (emphasis added): "A philosophy and way of living which seeks to exclude—as far as is possible and practicable—all forms of exploitation of, and cruelty to, animals for food, clothing or any other purpose; and by extension, promotes the development and use of animal-free alternatives for the benefit of humans, animals and the environment. In dietary terms it denotes the practice of dispensing with all products derived wholly or partly from animals."