Turn Instant Pot to SAUTÉ function. Add onion and oil. Stir occasionally until onions start to soften (about 5 minutes). Add garlic, thyme, and oregano. Stir often until fragrant (about 1 minute). Add drained tomatoes and stir until tomatoes begin to break apart. Add eggplant, zucchini, and bell pepper, and stir to combine.
Turn Instant Pot to MANUAL function and press HIGH PRESSURE. Cover the lid, turn valve to SEAL, and set time to 5 minutes.
Allow quick release. Open the lid and stir in basil, parsley, capers, and vinegar. Store in an airtight container in refrigerator or freeze.
For a single serving, heat 1 cup ratatouille in a skillet. Cook and stir often, until it begins to simmer. Make 2 small cavities, crack 1 egg into each cavity and reduce heat to low. Cover and cook until whites are set (about 3 minutes). Serve immediately with crusty bread. Enjoy! :-)