Combine 2 cups water and the salt in a glass or non-reactive bowl. Mix until the salt is dissolved. Add the carrots, cauliflower, serranos, garlic, celery and bell pepper to the salt water and stir to combine. Cover and refrigerate overnight.
Day 2, drain and rinse the vegetables. In a clean bowl, mix together the oil with the oregano and pepper. Add the vegetables and mix to combine. Allow to marinate overnight. Giardiniera will only get better with time. After 2 days at the most in the bowl, you can place in air-tight mason jars and keep in the fridge for at least 2 to 3 weeks.