The Only Time You Should Ever Stir Your Rice
Cooking rice can take some getting used to. It's a finicky grain and given that there is such a wide range of varieties, you may well find that once you've mastered, say, basmati rice, there's an even more challenging rice around the corner — sushi rice, for example.
The use of a rice cooker can be helpful in getting a consistent product, but these devices tend to be expensive and fancy ones can take up quite a bit of counter space. For many home cooks, the way to cook rice is on the stove.
One of the biggest pitfalls when it comes to making rice is having a finished product that comes out gloppy, clumpy, and sticky when you certainly didn't intend to make sticky rice to begin with. There's one habit above all others that will result in this type of mush and that's stirring your rice while it's cooking.
Why stirring will ruin your rice
Rice should be stirred once, and only once. When you introduce the rice to the water, it's important to give it a single stir to ensure that the grains don't clump together (via Eat This Not That). Breaking up potential clumps will help you avoid yielding little nuggets when the rice is all finished cooking. After that, give it a rest with the stirring. Stirring the rice will cause the grains to release their natural starches into the water, increasing the likelihood of the whole batch turning into a glutinous mess.
Bon Appetit seconds the notion about this common rice cooking mistake. Their advice is an emphatic NEVER stir your rice. It doesn't get any clearer than that. Meanwhile, another step that's important to take to cut down on the starch content of the rice is to give it a couple of rinses until the water is clear. This also helps in clearing some of the natural starches in the grains.