Bring a pot of salted water to a boil. Add the potatoes and cook until tender, approximately 10 minutes. Drain and let cool.
Bring a second, small pot of salted water to a boil. Add asparagus and blanch for one minute. Strain the asparagus and rinse with cold water. Dry thoroughly.
Add all vinaigrette ingredients to a sealable Mason jar. Seal the jar and shake vigorously.
Halve the boiled new potatoes and place in a large serving bowl. Add the asparagus, lentils and radish. Pour half of the vinaigrette onto the salad and toss to coat. Add the fresh herbs and Feta cheese. Add more vinaigrette as needed and season to taste.
