Place quinoa and water in a saucepan over medium heat. Bring to the boil. Reduce heat to low. Simmer, covered, for 12 minutes or until water is evaporated and quinoa is tender. Add coriander and mint, 1 tsp zest, half the marinade and half the chilli. Stir to combine. Set aside to cool.
Combine lemon juice, oil and remaining rind, marinade and chilli in a small bowl. Set aside.
Cut 3 diagonal slashes in the thickest part of snapper on both sides. Place two 80cm pieces of foil on the benchtop. Top each with baking paper. Place a fish in the centre of each.
Preheat an enclosed barbecue grill on medium-high. Stuff fish cavities with quinoa mixture and season. Top with lemon slices. Wrap fish in foil. Cook with barbecue hood down, turning fish halfway, for 12-14 minutes or until fish are just cooked through.
Steam broccolini and beans until tender-crisp. Place fish on a platter with steamed greens.