Take the endives and cut small rings (about 1 cm), starting at the top of the salad. Once you reach the bottom, make sure to take out the stalk, as it's quite bitter & hard. Wash the salad & place into a salad bowl.
Next, slice the radish rather thin and also add to the salad bowl. Cut the avocado into little squares (roughly 1cmx1cm) and add to the bowl as well.
Last, but not least, cut the feta cheese into squares as well and place them into the salad bowl. If you're vegan, simply leave the feta cheese or use any "fresh-tasting" vegan cheese you can find instead. Add the sunflower seeds on top of everything.
For the dressing, take a small jar and add mustard, salt, pepper, olive oil, lemon & balsamico vinagre. Close the jar & shake. Once you're happy with the consistency & taste simply pour over the salad. Mix well, serve & enjoy.