Begin by boiling sweet potatoes in a saucepan until they are very soft and easily mashable. Drain. In a bowl, mash sweet potatoes with olive oil and salt to taste until smooth.
Prepare the fish. Preheat oven to 425°F. Line a baking sheet with parchment paper.
Place veggie strips on one side of the baking sheet. Place fish on the other. Sprinkle the whole baking sheet with salt, pepper, and olive oil. Bake for 20 minutes. Once tray comes out of the oven, splash veggies with balsamic vinegar and mix.
Plate the dish. Swirl sweet potatoes on your plate. Top with fish, then veggies. Dot plate with some pesto.