Pesto is meant to be a little chunky, in that it doesn't need to be a perfectly smooth sauce. It can also depend on how you're going to use the pesto, but essentially you want something that is easily spreadable but not runny like a vinaigrette or anything. If yours feels a little too chunky, or even too runny, I say just let it sit for a while. Sometimes the sauce just needs some time for the ingredients to come together. For this nut-free pesto, letting the batch sit for even 20-30 minutes lets any of the chunkier rice pieces soften a bit and creates a more cohesive sauce. Bonus: That time also helps the flavors all come together and mingle!