Peel and finely dice the onions. Peel the cucumber, halve lengthwise, remove seeds with a tablespoon, then dice finely.
Heat 1 tablespoon of oil in a saucepan. Fry the onions in it until transparent. Steam mustard seeds briefly. Sprinkle with sugar and lightly caramelise. Add cucumber. Deglaze with vinegar, season with salt and pepper.
Bring to the boil, simmer open for about 20 minutes. Stir several times.
Meanwhile wash the meat, dab dry and cut into approx. 24 bite-sized cubes. Heat 2 tablespoons of oil in a frying pan. Fry the meat for 6-8 minutes. Season with salt and pepper. Sprinkle with honey and fry briefly over a low heat, turning.
Wash mint, shake dry and pluck off leaves. Stir the mint into the relish 2-3 minutes before the end of the cooking time. Season to taste with salt and pepper. Arrange the chicken cubes with the relish on spoons.