DRESSING:

1. Cut off an eighth of a large red onion, then slice that third thinly and add to a medium-sized bowl.
2. Add in the white wine vinegar (or red wine) and sea salt.
3. Whisk up this mixture for nearly a minute and then let sit for around 10 minutes.
4. After those 10 minutes, whisk in the mustard and olive olive. Keep whisking until the dressing is fully emulsified. Add some freshly ground black pepper.

SALAD:

1. Dice up one large cucumber (or two medium-sized) and two tomatoes. Add both to a salad bowl.
2. Cut off around a fourth of the red onion and dice. Add to bowl.
3. Take a handful of fresh herbs (dill, parsley or basil will do well), and chop well. Add to bowl.
4. Drizzle the dressing on the salad and mix well. Add a protein on top, or enjoy as a side salad.