Place quinoa in Multipurpose Steamer; stir in 1 cup hot water. Microwave on high, uncovered, until tender and water has absorbed, 12–15 min.
Meanwhile, grate and measure out 1 cup zucchini.
In bowl, combine mix with 1⁄2 cup hot water. Using the 2-in-1 Citrus Press, squeeze in 3 tbsp juice from lemon. Add zucchini; stir until combined. When cooked, stir in quinoa.
Preheat large fry pan over medium heat. When hot, add oil; scoop batter onto pan, making four burgers. Lightly press and flatten into shape. Cook until golden brown, 3–5 min per side.
Place patties on bottom halves of buns, then add burger sauce and toppings, if desired.