Bring the vinegar, sugar and salt to the boil in a pan. Add the radish, onion, jalapeños, garlic and mustard seed, simmer for approx. 10 mins., stirring occasionally. Leave the relish to cool.
Grill the sausages on all sides over/on a medium heat (approx. 200°C) for approx. 5 mins., cut the buns in half lengthwise and grill alongside for approx. 2 mins.
Combine the crème fraîche and honey mustard. Cut open the buns lengthwise, spread the sauce over the cut surfaces. Fill the buns with the cucumber, sausage, micro greens and relish.