To make the Russian salad: Bring a large pot of water to a boil over high heat. Working in batches, separately blanch fingerling potatoes (8–10 minutes), carrots (3–4 minutes), and peas (about 90 seconds), transferring each to an ice bath once finished. Lay vegetables out on a paper-towel-lined baking sheet and pat dry.
Slice fingerling potatoes and carrots into 1⁄2-inch rounds.
Place vegetables in a medium bowl and mix with mayonnaise, lime juice, and 1⁄2 tsp. salt. Refrigerate until ready to serve.
To make the tamales: Preheat oven to 400°F. Wrap Yukon gold potatoes in foil and bake 15–20 minutes, or until fully cooked. Peel off skins once cool enough to handle. In a large bowl, combine masa, cooked potatoes, 1 1⁄2 tsp. salt, 1⁄2 cup water, and mix with your hands until potatoes are broken up into chunks and combined with other ingredients but still recognizable. Slowly add oil to the mixture 1 tbsp. at a time, continue mixing with your hands, ensuring oil is combined before adding more. Add 1⁄2 cup water in the same manner and continue mixing until incorporated.
Spoon a 2-1⁄2 oz. portion of mixture in the center of a corn husk and wrap the sides up over the dough to encase it.
Heat a steamer pot over medium heat and place wrapped tamales inside with the lid on. Cook until firm to the touch and a toothpick inserted into the center comes out clean, about 45 minutes. Remove the corn husks, place a hefty spoonful of Russian salad on top, and serve with your favorite salsa.