Make the chicken marinade/sauce: in a small bowl combine 2 tsp garlic chili sauce, 2 tbsp fish sauce (or soy sauce), 2 tbsp maple syrup, the minced garlic, 2 tablespoons water, and a large pinch of black pepper; stir to combine.
Heat 2 tablespoons sesame oil in a large skillet over medium-high until shimmering.
Add the chicken strips to the hot skillet, season with a pinch of black pepper, and brown on all sides for about 5 minutes.
Pour the prepared sauce over the chicken, bring to a simmer, and cook until the sauce thickly coats the chicken, about 3–5 minutes; remove from heat and stir in 1/4 cup chopped basil.
Prepare the mango herb salad: in a medium bowl toss the sliced mango, 1/2 cup basil and cilantro leaves, sliced jalapeño, lime juice, 1 tablespoon toasted sesame seeds, and a pinch of Kosher salt.
Make the special sauce: in a small bowl whisk together 1/4 cup tahini, 2 tablespoons chili garlic sauce, 2 teaspoons maple syrup, and 1/4 cup water; thin with more water if needed and taste to adjust seasoning.
Assemble the banh mi: spread the toasted baguette pieces with the special sauce, top with the basil chicken, mango herb salad, pickled vegetables, and optional fried egg; close the sandwich and serve.