There's likely no one who quite knows how to push your buttons like your sister. Sometimes even as adults, sisters can be irritating. This behavior can lead to stress and tension within the relationship, making interactions difficult. She may still be playing a role from childhood, expecting you to follow suit. Perhaps your personalities clash. Regardless, it's important to find ways to handle this irritation during times when you and your sister will need to interact.
Focus on the Positives
As tempting as it may be to jump right in to the negative things your sister does next time you talk to her, it may do some good to think about the positive traits your sister has first. Spend some time reflecting on positive memories. You may want to include your sister in this activity to attempt to foster positive engagement at the beginning of an interaction if possible. This may not always work, but it's a nice place to start.
Setting boundaries can be a good way to limit how much irritating behavior you will put up with from your sister. "4 Tips for Setting Healthy Boundaries" on Psych Central's website instructs that you first identify what it is you won't put up with and then clearly and calmly let your sister know. Be specific and firm when laying down boundaries. Saying something like, "If you continue to interrupt me when we talk, this conversation is over" identifies the behavior and the consequence if it does not stop.
Get Family Support
Your family has likely noticed the behavior your sister displays that annoys you and it may even annoy them as well. Ask another family member how they manage to deal with the behavior or what they may suggest for you. They may know you and your sister well enough to help you gain good perspective including if there are any adjustments you could personally make.
Pick Your Battles
Some behavior, though annoying, may just need to be ignored, suggests "How to Deal with Annoying People" on Psychology Today's website. Choose carefully what you will spend your energy on in regards to addressing your sister's irritating behavior. There are likely some things your sister does or says, which even though they are annoying, they are not truly worth the time or energy it would take to address them. In this case, change the subject or leave the room. Remember, you can choose how and when you engage.