You can think of this version as a blend between Italian and Chicago-style giardiniera. I call it Italian for its nice list of crunchy veggies, vinegar, and herbs, and Chicago-style because we also add some olive oil and a little heat with pepper flakes (though that’s optional). Homemade giardiniera lasts about 3 weeks in the fridge and adds a crunchy, zesty bite to almost anything (we especially love it for burgers, pizza, and antipasto boards with sliced homemade focaccia).
1 ½ pounds (680g) cauliflower, 1 small-to-medium cauliflower, about 4 cups small florets
Half a large onion, chopped
5 cloves garlic, minced
8 ounces (226g) sweet bell peppers, seeds removed and chopped, about 2 cups
3 ribs celery, about 1 cup chopped celery
4 medium carrots, about 2 cups chopped carrots
1 tablespoon dried oregano
1 tablespoon fine sea salt or pickling salt
1 tablespoon granulated sugar
1/2 teaspoon fresh ground black pepper
1/2 teaspoon crushed red pepper flakes, optional
20 green pimento stuffed olives, sliced into rings
2 ½ cups (20oz or 590ml) white wine vinegar
1 ½ cups (12oz or 354ml) olive oil, not extra-virgin, see note
Prepare equipment: Set aside a large mixing bowl and a 2-quart canning jar (or two 1-quart jars).
Prepare the vegetables: Remove the stem and leaves from the cauliflower and then cut or pull it into tiny florets (about 1/4 inch). Mince the garlic, and then cut the remaining vegetables (onion, sweet peppers, celery, and carrots) into pieces no larger than 1/4 inch.
Combine the vegetables: In the large mixing bowl, combine the prepared cauliflower, onion, garlic, sweet peppers, celery, carrots, oregano, salt, sugar, black pepper, and pepper flakes (if using). Toss to combine, then let it sit on the counter for 30 minutes.
Make the brine: In a saucepan, combine the white wine vinegar and olive oil. Bring this mixture to a simmer over medium heat.
Add the brine to the vegetables: Carefully pour the hot vinegar and oil brine over the vegetable mixture. Use a spoon to press down all of the veggies, so they are submerged in the brine. Wrap the top of the bowl with plastic wrap and allow everything to cool completely to room temperature.
Add the olives and transfer to a jar: Once cooled, mix in the sliced green olives. Transfer the entire mixture to a 2-quart jar (or two 1-quart jars).
Store in the refrigerator: Refrigerate overnight (preferably upside down, set inside a bowl, to ensure even brining). The next day, turn the jar right-side up and let it stand for one more day in the fridge. They will only get better from here! As it sits, make sure the brine covers the vegetables. It lasts in the fridge for about 3 weeks.