Prepare slaw. Slice cabbage in half along the core. Carefully remove the cores and slice into thin ribbons. Add to a large mixing bowl with scallions, 2 tbsp apple cider vinegar, 1 1/2 tsp agave, 1/2 tsp salt, and 1/2 tsp pepper. Toss to combine. Let rest at room temperature.
Place a saucepan over medium-high heat and add vegetable oil. When hot, add red onion and a pinch of salt and sauté for 3 to 4 minutes, or until the onion is translucent and just browning at the edges. Add minced garlic and sauté for 1 minute more. Add ketchup, water, chipotle pepper, Worcestershire sauce, 1 tbsp apple cider vinegar, 1 1/2 tsp agave, dry mustard, and a large pinch of black pepper. Stir to combine. Bring to a simmer. Remove from heat.
Carefully pour the sauce mixture into a food processor or blender and blend until smooth, about 30 to 60 seconds. Pour the sauce back into your saucepan. Add daring pieces, bring mixture to a simmer, cover, and cook for 7 to 9 minutes or until the pieces are heated through and shred easily with a fork. Remove from heat.
Using tongs, carefully move the daring pieces to a clean cutting board. Shred the pieces with two forks and return them to the saucepan. Toss to coat. Cover to keep warm.
Place a large skillet over medium-high heat. Add vegan butter and swirl to coat the bottom. Add the slider buns cut side down and toast until golden brown, about 60 to 90 seconds. Move to a plate.
To assemble daring sliders, sandwich a heaping spoonful of pulled daring and vinegary slaw in between each toasted bun. Serve hot (with plenty of napkins).