Okay, here’s what I actually do every week. I buy three avocados at once—one is ripe, one is slightly firm, one is hard as a rock. I eat the ripe one immediately. The firm one goes in the fridge for later in the week.
For the cut half, I spritz with lime juice, press plastic wrap on like my life depends on it, and store it cut-side down on a plate. No brown spots. Ever. It’s not rocket science, but it is food science—and it works. Now go forth and enjoy your toast without fear. You’ve got this.