Place unpeeled whole potatoes in a medium pot and cover halfway with water. Cover the pot and bring to a boil. Then, continue cooking at a medium temperature for about 25 minutes, or until potatoes are easily pierced with a fork.
Do not overcook. The potatoes should still be firm and not be falling apart when pierced.
Remove from water and set aside to cool completely to room temperature.
Alternatively, you can steam the potatoes. In this case, you may peel them, place them on a steamer rack with enough water in the bottom of the pot. Cover and steam at medium temperature until potatoes are cooked. Steaming may take slightly less time to cook.
Once potatoes are cool, peel and dice them.
Pluck the leaves of the fresh tarragon from the stem. Finely chop them, if desired. Then, mix with all the vinaigrette ingredients in a small bowl. Let the vinaigrette sit for about 20 minutes or refrigerate for up to 2 days until ready to use.
To make the salad, combine all ingredients in a large mixing bowl: diced potatoes, diced gherkins/pickles, pomegranate seeds, cooked beans and lentils, and the watercress.
Toss gently to combine. Add the vinaigrette and gently stir to combine. Taste and adjust seasonings.
Serve immediately or refrigerate for up to 2 days, (see notes).
Notes
Potatoes can be cooked 1-2 days in advance. Keep them covered and refrigerated until ready to use.If you are making the salad in advance and refrigerating for more than a couple hours, I suggest not to add the watercress until you are ready to serve. Otherwise, they may start to wilt with the dressing.Else, you can also keep the dressing separate and drizzle it on the salad when ready to serve.Variations: You may double the amount of vinaigrette for bolder flavours. Substitute tarragon or add other herbs to the mix -- fresh basil, parsley or dill work well.Link to Tarragon Purple Potato and Mixed Bean Salad - https://veganlovlie.com/tarragon-purple-potato-and-mixed-bean-salad