Place yogurt in a medium bowl. Finely grate 1/2 tsp (2 mL) zest from lemon and add to yogurt. Squeeze out 3 tbsp (45 mL) juice from lemon. Stir 1 tbsp (15 mL) juice into yogurt along with chives, garlic, salt and cayenne. Divide between two deep soup bowls.
Divide salmon over yogurt in each bowl: arranging it in a row towards the centre. Beside salmon, in rows, arrange cucumber, beets, spinach, radish and avocado. Divide sprouts (if using) and place in centre of each bowl. Sprinkle each bowl with pumpkin seeds.
Whisk oil with 4 tsp (20 mL) lemon juice, curry powder and a pinch of salt. Drizzle dressing over bowls. Sprinkle with remaining lemon juice, if desired.