Add peperoncini, jalapenos, bell peppers, onion, and garlic to the food processor. Pulse until everything is finely chopped.
Dump out mixture into a saucepan and stir in peperoncini juice, lemon juice, and red pepper flakes. Cook over medium heat for about 3 to 5 minutes, until the vegetables are slightly softened.
Drain out any excess liquid with a fine mesh sieve. Let cool completely and place in a medium bowl. Stir in remaining ingredients and serve.
To store, place in an airtight container (I like to use a mason jar!) and store in the refrigerator for 1 to 2 weeks.