Prepare Mashed Potatoes: Place the Yukon potatoes into a medium saucepan and cover with cold water. (Keep in mind that you’ll need enough water to cover and cook the yams or sweet potatoes later.) Add 1 teaspoon salt and bring to a boil. Once boiling, add sweet potatoes or yams into the saucepan. Reduce heat and simmer for 15 – 20 minutes or until both potatoes and yams are soft when poked with a fork.
Chop the Veggies: While potatoes and yams are simmering, chop all the veggies, ham, and tarragon and set aside.
Put It All Together: Drain the potatoes and yams. Mash them all together in a large bowl. Add mayonnaise, ground black pepper, and all finely chopped ingredients into the same bowl. Combine until even.
Serve: Add more sea salt or pepper if desired. Let the salad cool, then refrigerate for a couple of hours before serving.