For the jalapeno jam: In a small saucepot, combine the jalapenos, sugar and marmalade and bring to a simmer over low heat. Simmer until the liquid reduces to a glaze, about 1 hour.
For the turkey burgers: In a bowl, combine the ground turkey, salt and pepper and mix well. Form the mixture into 6 patties.
Heat a cast-iron skillet over high heat until it begins to smoke. Add 1 tablespoon of the grapeseed oil to the pan and reduce the heat to medium. Add 3 of the patties to the pan and cook until the first sides are seared, 3 to 5 minutes. Flip and cook until the burgers are cooked completely through, about 5 minutes. Repeat with the remaining tablespoon grapeseed oil and the other 3 burgers.
Butter each of the buns on both sides and toast them in the hot skillet until golden brown.
Dress each of the bottom halves of the buns with lettuce, tomato, red onion and avocado. Place a burger on top of each dressed bun and top with 2 tablespoons of the jalapeno jam. Finish with a bun top.