Pat shrimp dry with paper towels. If desired, make 2 shallow diagonal slits on the underside and butterfly slightly so shrimp lay flat; leave tails on for presentation. Lightly season both sides with 1/2 tsp of the salt and the 1/4 tsp of the black pepper (reserve remaining for batter).

Make batter

In a medium bowl combine the all-purpose flour, cornstarch and rice flour. Add remaining 1/2 tsp salt and remaining 1/4 tsp black pepper and whisk briefly. Add the cold sparkling water and 4 small ice cubes and stir briefly with chopsticks or a fork; batter should be slightly lumpy and very cold. Do not overmix — small lumps keep the tempura light.

Heat oil

Pour vegetable oil into a deep pot or wok to a depth of about 3 inches (or enough to deep-fry). Heat oil to 350°F (175°C). If you don't have a thermometer, test with a small drop of batter — it should sizzle and float immediately.

Fry shrimp

Working in 2 batches to avoid crowding, dip each shrimp into the batter, letting excess drip off, then carefully lower into the hot oil. Fry until golden and crisp, about 2 to 3 minutes per batch depending on shrimp size. Use a slotted spoon to transfer cooked shrimp to a wire rack set over a baking sheet or paper towels to drain. Keep warm in a low oven (around 200°F / 95°C) while finishing the rest.

Spicy Thai Chili–Palm Sugar Glaze

Combine and dissolve

In a small saucepan combine the palm sugar, Thai red chili sauce, rice vinegar, soy sauce, lime juice, minced garlic and 2 tablespoons water. Warm over medium-low heat, stirring until the palm sugar dissolves and the glaze becomes glossy, about 3–4 minutes. Taste and adjust heat or sweetness: add more chili for heat or a pinch more palm sugar for sweetness. The glaze should be pourable but slightly syrupy.

Toss shrimp in glaze

Place the warm fried shrimp in a medium mixing bowl. Pour the warm glaze over the shrimp and gently toss with tongs or a spatula until each shrimp is evenly coated. Work quickly so the tempura remains crisp — toss just enough to coat and return to a wire rack for 30–60 seconds to let excess glaze set without making the batter soggy.

Seaweed Salad & Garnish

Prepare seaweed and onion

If using refrigerated store-bought wakame salad, give it a quick toss in its dressing and taste — if plain wakame, dress lightly with 1 teaspoon rice vinegar, 1/2 teaspoon sesame oil and a pinch of salt. Spread the seaweed salad in a shallow serving bowl or on individual appetizer plates. Scatter the finely chopped red onion evenly over or beside the seaweed salad.

Plate and garnish

Arrange 3 glazed tempura shrimp per appetizer plate (12 shrimp yields four appetizer servings) on top of or beside the seaweed salad. Sprinkle toasted sesame seeds and cilantro leaves over the shrimp and seaweed. Serve immediately with lime wedges on the side for squeezing.