How to Make It
In a small skillet, toast the cardamom, cumin and fennel seeds with the crushed red pepper over moderate heat until the spices are fragrant, about 1 minute. Transfer to a spice grinder and let cool. Grind to a powder.
In a small bowl, mix the ground spices with the olive oil, vinegar, shallot and garlic and season with salt and pepper. Stir in the mango.
Season the scallops with salt and pepper. In a large skillet, heat the vegetable oil until shimmering. Add the scallops and cook over high heat, turning once, until browned, about 2 minutes per side. Transfer the seared scallops to a large plate.
In a large bowl, combine the arugula, tomatoes and jicama. Add half of the mango dressing and toss well. Mound the arugula salad on plates and arrange the seared scallops on top. Drizzle the scallops with the remaining mango dressing and serve at once.