Curried Sweet Potato and Corn Cakes with Pistachio-Yogurt Sauce

Preheat the oven to 200°C (400°F) and line a baking sheet with parchment paper.

Arrange the whole unpeeled sweet potatoes on the prepared baking sheet and roast at 200°C (400°F) for 45 minutes until tender throughout.

Remove the sweet potatoes from the oven and allow them to rest on the baking sheet for 15 minutes until cool enough to handle comfortably.

Peel the roasted sweet potatoes by stripping away the loose papery skins, discarding the peels.

Transfer the sweet potato flesh into a large mixing bowl and mash with a potato masher until predominantly smooth with small textured pieces remaining.

Heat 15 ml of vegetable oil in a small skillet over medium heat to 165°C (330°F), then stir in the brown mustard seeds, cumin seeds, minced serrano chili, grated ginger, and chopped curry leaves, sizzling for 45 seconds until the mustard seeds crackle and leaves turn crisp.

Combine the shelled pistachios, whole milk Greek yogurt, cilantro, mint leaves, minced garlic, 10 ml lemon juice, toasted ground cumin, 2 g fine sea salt, and 20 ml cold water in a food processor, processing for 60 seconds until emulsified into a pale green, velvety sauce.

Transfer the blended pistachio-yogurt sauce to a small bowl, cover securely, and chill in the refrigerator for 20 minutes to meld flavors.

Pour the hot tempered spice oil into the mashed sweet potato, then add the sweet corn kernels, chickpea flour, white rice flour, ground coriander, ground turmeric, garam masala, chopped cilantro, remaining 15 ml lemon juice, and 4 g fine sea salt, mixing thoroughly until a stiff, cohesive dough forms.

Weigh the dough on a digital kitchen scale into 8 equal portions of roughly 90 g each, and shape each portion with clean hands into a flat circular cake roughly 2 cm (0.8 inches) thick.

Heat 15 ml of vegetable oil in a cast-iron skillet over medium-high heat to 180°C (356°F), place 4 shaped cakes into the skillet without crowding, and sear undisturbed for 4 minutes until a deep golden-brown crust forms on the bottom.

Flip each cake carefully with a spatula and cook the second side for 3 to 4 minutes until crisp, deep golden, and the center reaches an internal temperature of at least 74°C (165°F) on an instant-read digital thermometer.

Transfer the cooked cakes to a warm plate, add the remaining 15 ml of vegetable oil to the cast-iron skillet, and fry the remaining 4 cakes for 3 to 4 minutes per side until crisp, golden, and reaching 74°C (165°F) internally.

Spread approximately 70 g of chilled pistachio-yogurt sauce across the surface of each serving plate, and arrange 2 warm sweet potato cakes directly over the sauce.

Garnish the plated savory cakes with additional fresh cilantro leaves or chopped roasted pistachios, and serve immediately while the cakes remain hot and crisp.