Mayo, make up to one day ahead.
Thoroughly combine all ingredients. Top with plastic wrap, pushing down to contact mayo. Cover bowl and put in fridge til ready to use.
Pickles, make at least an hour prior or up to one day ahead.
Thoroughly combine the warm vinegar, sugar, salt & pepper, stirring til sugar is dissolved. Add the vegetables, cover and put in fridge. Bring up to room temp and drain prior to use.
Vegetables (excl shallots), prep shortly before use.
Thinly slice shallots and fry til golden brown. Can be done up to one day prior but bring up to room temp prior to use.
Meatballs, prep up to one day before cooking In mixing bowl combine nuoc mam, Sriracha, sugar, cornstarch, pepper, salt. Use mini-chop to combine basil, garlic, scallions, add to mixing bowl and combine. Add ground pork, combine but avoid overmixing. Gently form small meatballs using 1tbs measure. Cover and chill. Using large skillet, cook meatballs in small batches, leaving room between so they lightly brown but do not crisp. Cover and keep warm til serving.
Patties, make shortly before cooking In mixing bowl combine nuoc mam, soy sauce, 5-spice, sugar, corn starch, lime juice. Use mini-chop to combine chile, garlic, ginger, lime zest, add to mixing bowl and combine. Add ground pork, combine but avoid overmixing. Gently form six patties. Cover and chill. Lightly grill patties. Cover and keep warm til serving.
Bread, prep just before serving If making custom sandwiches, cut the loaves into serving portions. Then cut in half lengthwise, hollow-out. Crisp with cut-sides down in 450 oven for 5 minutes just prior to serving.
Assembly, have at hand at room temp: mayo, pate or liver sausage, fresh vegetables, shallots, drained pickles. Warm meat, warm bread. You'll work from the bottom-half of the bread upwards, roughly in order (don't overdo the meat, you should be able to taste each separate element in the finished sandwich):
Mayo Light spread liver sausage or pate Layer of cuke Layer of either halved meatballs, cut-side down /or/ crumbled patties (not both)
Shallots Pickles Sliced chiles to taste 4-6 Sprigs of cilantro Bottle of Sriracha (optional drizzle to taste)