Notes: The citric acid in lime juice firms fish and makes it opaque, so ceviche looks and tastes cooked but isn't. As with sushi, if you want to be extra careful, shop at a trusted market, tell the fishmonger that you plan to eat the fish raw, and always use safe kitchen practices.
1. In a medium bowl, combine fish and 2 tbsp. each of lime and lemon juice. Cover and refrigerate at least 3 hours and up to 6, stirring occasionally.
2. Meanwhile, mix olive oil, oregano (rubbed between your palms first if the flecks are large), and pickled jalapeño juice in a large bowl.
3. Drain fish in a colander, discarding juices, and add to olive-oil mixture. Toss to coat.
4. Add pickled jalapeños, onion, tomatoes, cucumber, olives, cheese, serrano, and cilantro. Peel avocado, cut into 1/2-in. cubes, and toss gently with remaining 1 tbsp. lemon juice; add to bowl and toss ceviche gently and thoroughly. Season to taste with salt and remaining 1 tbsp. lime juice. Serve with tortilla chips and hot chile sauce.
Note: Nutritional analysis is per serving.