Slice the tomatoes, lengthwise into quarters, remove and discard seeds and core.
Dice tomatoes and onions into small equally sized pieces and place them in a medium-sized bowl.
Slice the jalapeno, remove the ribs and seeds and dice into small pieces, add them to the bowl.
Dice cilantro and add it to the bowl.
Add lime juice, lime zest, red pepper flakes (if you want it hot), and salt and pepper.
Toss all ingredients, cover with plastic wrap and refrigerate for 30 minutes or serve immediately.