Preheat oven to 350°. Line a baking sheet with parchment. Stir sriracha, maple syrup, lime juice, and olive oil together in small bowl.
Arrange sweet potato slabs on baking sheet and brush with about 1/4 of sriracha mixture. Bake 15 minutes. Flip, brush with another 1/4 of sriracha mixture, reserving the remaining half, and bake another 15 minutes, until tender. Remove from oven and sprinkle lightly with salt.
While sweet potato slices roast, place all ingredients for cilantro lime mayo into food processor bowl and blend until smooth, scraping down sides of bowl as needed.
Slather bread slices with cilantro lime mayo and stuff with sweet potato slabs, and tomato slices.
Drizzle with reserved sriracha mixture.