2 large cucumbers, peeled and thinly sliced
1 sweet onion, thinly sliced
1 tablespoon sea salt
1 1/2 cups mayonnaise, or more to taste
2 tablespoons vinegar
1 tablespoon white sugar
1 teaspoon dried dill weed
1 teaspoon garlic powder
1 teaspoon ground black pepper
Mix cucumbers, sweet onion, and sea salt together in a bowl. Cover bowl with plastic wrap and let sit for 30 minutes.
Turn cucumber mixture into a colander set over a bowl or in a sink; let drain, stirring occasionally, until most of the liquid has drained, about 30 minutes more. Transfer drained cucumber mixture to a large bowl.
Stir mayonnaise, vinegar, sugar, dill, garlic powder, and black pepper together in a bowl with a whisk until smooth; pour over the cucumber mixture and stir to coat vegetables with the dressing.
Cover bowl with plastic wrap and refrigerate at least 2 hours.