Preheat the oven to 450 degrees F.
In a bowl, toss the sweet potato slices with about 2 tsp of olive oil and a pinch of salt. Toss together until all of the slices are thoroughly combined in the salt and olive oil.
On a sheet pan, lay out the sweet potato slices with the largest flat side facing down. Roast in the oven for 15 minutes. Check on them after 15 minutes, and then flip to roast for another 10 minutes.
While the sweet potatoes roast, prepare the guacamole. Scoop the "meat" out of the avocado and place it into a large bowl or mortar and pestle. Mash the avocado until creamy. You can leave chunks or completely mash it out. The texture is up to what you like!
Add a pinch of salt (about 1/4 tsp if you want to measure) and lime juice and combine. Taste to make sure you approve of the salt and zest level. If you want more lime or salt, season as you'd like and mix together.
Add the onion, tomato and garlic, if using. Mix together and set the bowl aside.
Pat the shrimp dry with a paper towel and make sure they are dry on both sides. Season with a small pinch or crank of salt and set aside.
Season a skillet with olive oil (or an oil of your choice) on medium high heat.
Once the oil is shimmering, add as many shrimp that will fit onto the pan. Sear for 1-2 minutes, until the side on the pan is pink and crispy golden brown. Flip the shrimp and sear for another 1-2 minutes until the entire shrimp is cooked through (AKA pink) and both sides are crispy golden brown. Repeat with all of the shrimp.
Remove the sweet potatoes from the heat once they are golden brown and tender inside. TIP: If you prick them with a knife, the sweet potato "meat" should be soft and not resist the knife.
Plate 2-3 sweet potato slices on a plate. Spread each slice with guacamole and top with seared shrimp. Add cilantro on top of the shrimp, if using. Repeat with the other slices and serve immediately.