This tutorial features the Feast Plugin, which enhances and extends your theme to improve SEO, pagespeed, accessibility and user experience.
When you're updating posts, you want to be as thorough as possible to avoid having to re-edit multiple times. Remembering all of what needs to be done is impossible though - so we've created a Recipe Update Checklist available exclusively through the Feast Plugin.
For new posts, use the Recipe Post Template for a pre-built post structure, instead of writing a new recipe from scratch.
Note: checklist has been blurred as these will be updated frequently based on ongoing best practices. Please visit the "Recipe Update Checklist" page in the Feast Plugin for the current list.

General
Make sure you have all your alt tags, proper image sizes, avoid over-stuffing keywords, and more, with the general section.
This is continually updated with current best practices so make sure to revisit it every so often.
Content
Every recipe has a basic set of questions that should be answered to pre-empt the readers questions and provide the highest quality content for Google and readers.
Why is having topically-relevant, quality on-page content important? Here's a quote from Google's John Mueller:
Also check out these great content ideas from FoodBloggerPro.
Content rot
Content rot is a concept we use to encapsulate the idea that the industry is always evolving, and what is considered "acceptable" by todays standards will be outdated in a couple years.
As a broad gauge, we'd say that the value of content decays at about 20% per year. This means that you should be updating around 20% of each post on a yearly basis to keep it up to modern standards.
This can mean entirely reshooting a non performing post after 5 years, or reshooting the photos after 3 years, or simply addressing new user questions/comments in the post content every year.
This certainly isn't universal - some sites have 5-6 year old content that's still doing well because it was done to extremely high standards for the time.
As always, it's generally best not to edit your top 5-10 traffic-driving posts. Focus your content update efforts on worse performing posts, which have more upside and less downside.
Modified dates
See this post on modified dates.
Pagespeed
Double check your pagespeed scores to ensure you haven't embedded anything that would penalize you, and prevent you from ranking.
Timing
You should not update your "unicorn" posts - that is, posts that are bringing in substantial traffic to your website. This will vary by website, but generally any post bringing in more than 10% of your traffic is too important to update. The risk of losing this level of traffic generally outweighs the potential benefit.
With that caveat, most posts should be updated once per year, generally 1-2 months before the keyword "trends" seasonally.
Using the Holidays is a great way to ensure your content gets resurfaced seasonally, when it's relevant.
URVASHI PITRE says
Where are these checklists available? I've updated but didn't see them right away.
Skylar says
If you're running a recent version of the themes, it will be under the theme menu in the sidebar under "Recipe Update Checklist".
If you're running a non-Feast theme, it will be in the "Settings" menu in the sidebar under "Recipe Update Checklist".