As a new vegan, I can tell you from personal experience that a whole foods plant-based diet has no limits. The best thing to do to heal leaky gut is to make sure you have no parasites, don't have a bad bacterial or fungal overgrowth, and eat whole foods. Then, fasting because the gut heals its lining every 5-7 days, so if you fast for a day or a week, after a while you are healing any troubled areas. But you really have to clean up your gut by eating well and going through detox of any bad stuff.
Asking about the HCL makes me wonder that you have low stomach acid? Is that why you're asking?