Select your avocados based on when you plan on making the dressing. If you want to prepare it the same day, choose ripe (not over-ripe) avocados. A ripe avocado will be fairly firm, but will yield to light pressure. The skin will be snug to the fruit, not brittle or pulled away. A perfectly ripe avocado will be neither hard nor mushy. My husband always checks to see that the stem is still intact on the avocados he buys. If it has been removed, the avo will tend to over-ripen from the top, so he only buys the ones with the stems. There’s a fine line between ripe and over-ripe and you’ll know it when you cut into an avo. One of the first signs of it being too ripe is the color of the flesh. Once those brown spots show up, it’s too late. Another way to check if it’s over ripe is by smell. An acrid or sour smell is a sure sign that you won’t be using that avocado. If you don’t plan on using your avocados the day you buy them, it’s better to error on the side of caution and choose firmer ones. If you have ripe avos that you won’t use the same day, put them in the fridge. It will slow down the ripening process and might give you a few extra days to use them.