Cook the quinoa in boiling salted water according to the instructions on the packet for 10-15 minutes. Wash and clean the mangetouts and cut them diagonally in half. Wash the cucumber. First cut lengthwise into slices, then diagonally into strips.
Wash the coriander, shake dry and chop finely.
Onions peel, halve lengthwise and cut into fine strips. Pluck the roast beef into pieces. Drain quinoa in a sieve, drain and let cool. Mix with mangetouts, cucumber, coriander and roast beef.
For the marinade, peel and finely chop the garlic. Mix with vinegar, lime juice and soy sauce, fold in oil. Season to taste with salt, pepper and sugar. Mix with quinoa meat salad.