Preheat oven to 375°F .
On a large sheetpan, combine cauliflower or romanesco and potatoes. Add ½ tsp salt, ¼ tsp black pepper, and and 2 tbsp olive oil. Toss everything together and spread it out evenly on the pan.
Bake for about 35-40 minutes or until fork tender and lightly browned.
Meanwhile, in a wide, shallow bowl, combine 1 tbsp olive oil with ¼ tsp salt, ¼ tsp black pepper, and the zest and juice from lemon. Add salmon, toss to coat, then cover and set aside.
Remove sheet pan from oven and transfer roasted vegetables to a large bowl. Place salmon on sheet pan. Bake for 5-10 minutes until salmon flakes easily with a fork and internal temperature of at least 130°F.
While salmon is roasting, add pesto to the bowl of vegetables and toss to coat. Divide into serving bowls.
Divide salmon into bowls and top each bowl with a dollop sour cream.