Preheat the oven to 450°F. Halve the potatoes (quarter if large). Halve and core the peppers; toss with a drizzle of oil; season with S&P. On a lined sheet pan, toss the potatoes with a drizzle of oil; season with ⅓ of the spice blend and S&P. Arrange in a single layer and roast, 10 to 12 min. Remove from the oven, add the peppers and continue cooking, 10 to 12 min., until tender when pierced with a fork. Once cooked, using a fork (or potato masher), gently smash the potatoes until flattened but still in one piece.
While the vegetables roast, zest and juice the lime. Small-dice the tomato. Cut off and discard the root end of the scallion; thinly slice, separating the white bottoms and green tops. Finely chop the cilantro leaves and stems. In a small bowl, make the bravas sauce by combining the mayonnaise, ½ tbsp lime juice, 1 tsp water (double the lime juice and water for 4 portions) and up to ½ the lime zest and the white bottoms of the scallion (to taste). Season with ½ the remaining spice blend and S&P to taste.
While the vegetables continue to roast, in a medium bowl, combine the tomato with ½ tbsp oil (double for 4 portions), up to ½ the cilantro (to taste), as many of the remaining white bottoms of the scallion as you’d like and up to ½ tbsp lime juice (to taste, double for 4 portions). Season with S&P to taste.
In a large pan, heat a drizzle of oil on medium. Pat the shrimp dry with paper towel; season with the remaining spice blend and S&P. Add the shrimp* in a single, even layer and cook, 1 to 2 minutes per side, until opaque and cooked through. Sprinkle the cooked shrimp with as much of the remaining lime zest as you’d like.
Switch the oven to broil. Return the sheet pan of roasted vegetables to the oven and cook, 3 to 4 minutes, until the potatoes have browned. Place the smashed potatoes, roasted peppers and cooked shrimp on a serving platter. Serve the bravas sauce and the pico de gallo on the side. Garnish with as many of the green tops of the scallion and as much of the remaining cilantro as you’d like. Bon appétit!