Wash, pierce with a fork, and microwave the sweet potatoes and Yukon Gold potatoes until tender. Boil the red potatoes in salted water until tender. Do not overcook the potatoes, or they will not hold up in the salad. Drain red potatoes and chill all three types overnight.
Peel the sweet potatoes and Yukon Golds, and dice into 1/2 inch cubes. Cut red potatoes into fourths. Place all potatoes into a large bowl.
Slice red onion thinly and place into a colander. Sprinkle the salt on the onion and let it sit in the colander for 30 minutes to drain. Squeeze onion to remove excess water, and add to the bowl with the potatoes. Mix in the garlic, jalapeno, lemon juice, mayonnaise, curry powder, parsley and pepper, and chill until ready to serve.