A prep cook in Portland mentioned they never salt their mirepoix until the onions are translucent.
I tried it with a beef stew base yesterday, and the onions softened much faster without drawing out moisture, which really deepened the overall flavor in under 30 minutes.
Yeah that Austin style is no joke. I heard some folks down there even throw in a square of dark chocolate at the end, melts right in. Gives it this deep, rich flavor without being sweet. My cousin swears by a splash of coffee too, says it makes the spices pop. Honestly might try both next time I make a pot.