第三食肉[轻]戒:若佛子,故食肉,一切肉不得食。夫食肉者,断大慈悲佛性种子,一切众生见而舍去。是故一切菩萨,不得食一切众生肉。食肉得无量罪。若故食者,犯轻垢罪。
— 释迦牟尼佛
《梵网经菩萨戒本》The Third [Light] Precept Against Eating Meat: If [as] Buddhas’ [Bodhisattva] disciples, [of] intentionally eating meat, all meat must not [be] eaten. Those [who] eat meat, sever [the] great loving-kindness [and] compassion [of their] Buddha-nature’s seed, [with] all sentient beings [who] see [them] abandoning [them]. Therefore, all Bodhisattvas, must not eat all sentient beings’ meat, [with] eating meat attaining immeasurable transgressions. If [there are] those intentionally eating [it, they] commit [a] light defiled transgression.
— Śākyamuni Buddha
(Brahmā Net Sūtra: Bodhisattva Precepts’ Text)
In many Asian countries, many mock meats have already been around for ages. However, originating from the West, it is hard to miss the promotion of plant-based meats in recent years, which are, depending from case to case, supposedly more environmentally sustainable forms of ‘beef, fish, chicken, pork’ and such. One of the key differences between earlier mock meats and recent plant-based meats is that the latter arose from more research to mimic meats’ flavours and textures, even trying to match them in nutrition. When browsing at supermarkets, more and more brands of plant-based meats seem to pop up by the day. Naturally, for veg(etari)ans, there is some rejoice and excitement.

However, for more conscientious Buddhists, there will be some disappointment upon reading their ingredient lists, as many western brands carry garlic and/or onion in their ‘meats’, which are roots ‘frowned upon’ in the Buddha’s teachings, such as the Śuraṅgama Sūtra《楞严经》. Even if these ‘meats’ do not contain actual meat and alcohol, and are fully vegan, they might still contain the Five Pungent Roots (五辛) of garlic (大蒜), leek (革葱), onion (慈葱), chive (兰葱) and asafoetida (i.e. hing: 兴蕖). Unfortunately, when eaten cooked, they give rise to lust, and when eaten raw, they increase anger. Heavenly sages (天仙) will be disgusted by their foul stench, and all far depart from those who eat them, not coming to protect them.
Many hungry ghosts (饿鬼) and such will be attracted to eat next, by licking and kissing their lips. Always with ghosts dwelling, their blessed virtues (福德) will by the day dissipate. Great powerful demon kings (大力魔王) will manifest as Buddhas to speak the false ‘Dharma’ to them, that slanders the prohibitive Precepts, that praises the Three Poisons (三毒) of lust (greed), anger (hatred) and delusion (ignorance) instead. When their lives end, they will become their family members. When their demonic blessings exhaust, they will fall into the Uninterrupted Hell (无间地狱) – in the worst-case scenario.

With such grave spiritual disadvantages, even when eating less meat, if eating plant-based meats means eating more pungent roots, that can give rise to these problems, it is hard to say such plant-based meats should be celebrated and encouraged. However, according to the Bodhisattva Precepts’ (菩萨戒) sequence, which speaks of different weightages in priority, (as in the opening and closing quotes here), the Buddha did teach abstaining from meat before abstaining from the roots. That said, if many of the roots are consumed regularly, their cumulative negative effects might even become equivalent to those from eating meat.
Some plant-based meats are higher in salt content too, which is not so good for health. It might be better to create plant-based burger patties and such personally. Just go easy on the salt, skip the pungent roots and alcohol. As it is always better to consume the WFPBD (Whole Food Plant-Based Diet) for optimum and natural nutrition, may none get too carried away by commercial plant-based meat trends. It is also better for the environment to consume wholefoods directly, as there is no excess energy expended on processes to create plant-based meats, (which helps to explain their cost). In short, down to earth eating of natural plant foods is the best!

第四五辛[轻]戒:若佛子,不得食五辛:大蒜、革葱、慈葱、兰葱、兴蕖。是五辛,一切食中不得食。若故食者,犯轻垢罪。
— 释迦牟尼佛
《梵网经菩萨戒本》The Fourth [Light] Precept Against Eating The Five Pungent Roots: If, [as] Buddhas’ [Bodhisattva] disciples, [they] must not eat [the] five pungent [roots, of garlic, leek, onion, chive and asafoetida (i.e. hing)]. These five kinds, within all foods, must not [be] eaten. If intentionally eating [them, they] commit [a] light defiled transgression.
— Śākyamuni Buddha
(Brahmā Net Sūtra: Bodhisattva Precepts’ Text)
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https://thedailyenlightenment.com/2016/10/how-should-all-aspiring-for-buddhahood-eat-and-drink
A Brief History of the Love-Hate Relationship with Mock Meats
https://thedailyenlightenment.com/2011/03/a-brief-history-of-the-love-hate-relationship-with-mock-meats
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https://thedailyenlightenment.com/2018/10/which-is-more-allowable-for-consuming
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Living A Whole Food, Plant-Based Life
https://nutritionstudies.org/whole-food-plant-based-diet-guide