01 - Combine ground turkey, finely chopped onion, minced garlic, chopped parsley, smoked paprika, ground cumin, salt, and black pepper in a mixing bowl. Mix gently until just combined.
02 - Shape the mixture into four equal-sized patties.
03 - Heat olive oil in a large skillet or grill pan over medium heat. Cook the patties for 5 to 6 minutes per side until golden brown and cooked through, reaching an internal temperature of 165°F. Remove from heat and let rest.
04 - In a bowl, mash avocados until mostly smooth. Stir in diced tomato, red onion, jalapeño if using, chopped cilantro, lime juice, salt, and freshly ground black pepper. Adjust seasoning as needed.
05 - Lightly toast the burger buns if desired.
06 - Layer lettuce on the bottom bun, place a turkey patty on top, add a generous spoonful of guacamole, sliced tomato, and red onion. Cover with the top bun.
07 - Serve immediately while warm.