Wash and scrub potatoes. Chop them into ½-inch cubes.
Cover diced potatoes with water and add a few teaspoons of salt. Bring water to boil and continue cooking until just tender, about 3 to 4 more minutes.
Drain and run potatoes under cold water. Spread potatoes on a baking sheet to cool for 5 more minutes.
Add potatoes to a large bowl and toss with oil, cumin, coriander, paprika, marjoram, red onions, parsley, lemon juice and a small pinch of salt.
Serve immediately or cover in plastic wrap and refrigerate for 3 hours before serving.