Place sweet potatoes in a pot and fill with water. Bring to a full boil and cook 5 to 8 minutes, until potatoes have softened but are not cooked through. Transfer potatoes to a cutting board and allow them to cool enough to handle. Once cool, slice into 1/4-inch thick rounds. Coat sweet potato slices with oil and sprinkle with sea salt.
Preheat the grill to medium-high. Add the ingredients for the shrimp to a sealable bag and shake well to combine. Allow shrimp to marinate while grill is heating.
Once hot, place the sweet potato slices on the grill. Grill for 5 to 8 minutes per side, until deep char marks appear and sweet potatoes are cooked through. Transfer to a cutting board. Once cool, chop the sweet potatoes to desired size peices.
Place shrimp on the hot grill and grill 2 minutes per side, or until cooked through.
Divide rice between 3 to 4 bowls. Top with grilled shrimp and sweet potato, avocado, cabbage, tomatoes, and fresno chiles, lime wedges, and cilantro. Drizzle with sriracha if desired.