The flavors of southeast Asian cooking, notably dishes such as pad thai (“pad” just means noodles, so “pad thai” just means “Thai-style noodles”) can easily be replicated by combining chili sauce (sriracha in particular, less so the vinegar-heavy tabasco-style sauces in tex-mex cooking) and peanut butter. Add cabbage for texture.
Bread is your choice, but to evoke a banh mi, I’d use a crusty roll if available. Then, just slather in some PB, squirt in some chili sauce and stick a cabbage leaf in the middle. Cheap and above-mediocre