1. Adjust oven rack to highest position and heat broiler to high. Pat squid and shrimp dry with paper towels. Toss with oil and season with salt and pepper. Arrange seafood in a single layer on a rimmed baking sheet. Broil until cooked through and charred in spots, about 5 minutes. Let roasted seafood cool.
2. In a large bowl, combine tomato juice, lime juice, ketchup, chili sauce, cilantro, scallions, tomato, oregano, hot sauce, garlic, and jalapeño. Stir until well combined. Add seafood and mix well. Cover and refrigerate for at least 1 hour and up to overnight.
3. To serve, top with diced avocado and oregano leaves. Serve with tortilla chips on the side.