Begin by making the marinated tempeh. Stir the soy sauce, Worcestershire sauce, maple syrup, and garlic powder together in a shallow dish. Add the tempeh cubes and toss to coat. Allow to marinade for about 30 minutes, stirring occasionally to redistribute the sauce.
While the tempeh marinates, make the Russian dressing by placing the cashews, ⅓ cup of water, ketchup, red wine vinegar, Worcestershire sauce, and hot sauce together into a blender. Blend until smooth, thinning with a bit of extra water if needed. Add in the relish and pulse just to mix it in. Season with salt and pepper to taste.
Once the tempeh has finished marinating, coat the bottom of a medium skillet with oil and place it over medium heat. When the oil is hot, add the tempeh to the skillet and cook for about 10 minutes, flipping once or twice, until the tempeh is browned on multiple sides.
To assemble the wraps, slather each tortilla with a layer of the Russian dressing. Cover the layer of dressing with a few lettuce leaves. Arrange a fourth of the temeph cubes in a strip down the middle of the wrap, then spoon a strip of sauerkraut next to the tempeh. Arrange a few avocado slices over the tempeh and sauerkraut. Wrap and enjoy.
You'll have more than enough dressing for four wraps. The extra makes a great salad dressing, and also freezes well when placed in a sealed container.