>>21454297 (OP)>Is soy sauce the best condiment for plain white rice?Ehh, no. Maybe it's fresh salsa, or the sauce from your main.
I like the mustard-curry sauce from Chicken Kitchen and Pollo Tropical and I often make the sauces even better at home when I get a rotisserie chicken. Mine will have lime zest, ginger, mango chutney, sour cream or yogurt, with the mustard and curry powder, kicked up a notch. there's another good sauce you get with Peruvian chicken, yellow or green aji pepper sauce. At home you incorporate the sensibilities of "a la huancaina" style with cream cheese, queso fresco, cream, and your aji pepper pastes.
Otherwise, itt might be super chili crisp or 7 spice togarashi, or a seasoning called furikake.