Cook Wild Rice Blend (Note: this can be done up to 2 days in advance to save time.)Combine wild rice blend and 1 1/2 cups water or broth in a medium saucepan; bring mixture to a boil. Cover with a tight-fitting lid and reduce heat to maintain a low simmer; cook for 45 minutes. Transfer cooked rice to a bowl, and let cool completely.
In a large bowl, use a potato masher or fork to thoroughly mash cannelloni beans. Add cooked and cooled rice, eggs, breadcrumbs, tahini, tomato paste, Worcestershire sauce, cumin, smoked paprika, black pepper, salt, and oregano. Thoroughly mix until well-combined. Transfer bowl to the refrigerator and chill for a minimum of 30 minutes, or up to 24 hours (overnight).
For slider-size burgers, use a 1/3 cup measure to divide and form mixture into 8 uniform patties. For regular burgers, use a 1/2 cup measure to divide and form 6 uniform patties. Place patties on a parchment-lined baking sheet. (Note: If burgers aren't holding together well, chill for another 20 to 30 minutes.)
Heat 2 Tbsp. oil in a large skillet over medium heat. Once the oil is shimmering, add half of the burger patties. Cook 5 to 6 minutes, or until golden brown. Gently flip, and cook for another 5 minutes. Add remaining 1 Tbsp. oil and repeat with remaining patties.
Meanwhile, prepare Tahini Special Sauce by combining tahini, Thai sweet chili sauce, lemon juice, and garlic in a small bowl; stir to combine. Gradually stream in 2 Tbsp of warm water, whisking constantly, until smooth and creamy.
Assemble burgers by spreading Tahini Special Sauce on both the top and bottom of the bun. Add 1 wild rice patty to the bottom bun, and top with pickled red onion, avocado, and arugula, if desired. Cover with top bun and enjoy!