Thank you for asking this question before proceeding with your batch. While using the oven might seem like a convenient and mess-free shortcut, I must strongly advise against sterilizing glass canning jars in the oven.
From a kitchen safety standpoint, major food preservation authorities such as the USDA and the National Center for Home Food Preservation explicitly warn against oven sterilization for two critical reasons:
First, standard glass canning jars are engineered for moist heat, not dry heat. Dry heat in an oven can weaken the glass structure, causing micro-cracks or even causing the jars to shatter dangerously while in the oven or later when filled with hot escabeche.
Second, dry heat is significantly less effective at conducting heat and killing microorganisms than boiling water or steam. An oven has cold spots and uneven air circulation, meaning the jars may not reach or maintain a reliable temperature throughout to guarantee true sterilization.
To ensure your escabeche is safe for long-term storage and to protect yourself from shattered glass, the standard and safe method is water-bath sterilization. Simply place your clean jars right side up on a rack inside a large pot, submerge them completely under at least one inch of water, bring the water to a rolling boil, and boil them for 10 minutes (adding 1 additional minute for every 1,000 feet of elevation above sea level). Keep the jars in the hot water until you are ready to fill them with your hot preparation to avoid thermal shock.
