The plural of tomato is tomatoes.
The fruit of a plant belonging to the Solanum family, characterized by a lightly acidic taste and pulpy texture. It is usually red in color and contains a lot of seeds.
Words ending in -o in the English language usually form their plural by adding the suffix -es. Although there are some exceptions (such as piano and photo), the word tomato has a regular plural form.
The plural of tomato is therefore tomatoes.
Singular Example: Although often thought of as vegetables, a tomato is actually a fruit since it develops from the fertilized ovary of a flower..
Plural Example: Tomatoes are known for their rich red color but they can come in many different forms such as yellow, pink, purple, black and even white.
The Guinness world record for “most tomatoes harvested from a single plant over one year” was an impressive 32,194 tomatoes from a single plant weighing 522.464 kg (1151.84 lbs)!
Sources:
https://www.dictionary.com/browse/tomato
https://www.campbellsoup.co.uk/blog/fun-facts-about-tomatoes/