Prepare dipping sauce (see below) and set aside. Peel sweet potatoes and cut into 1/4-inch-thick wedges. Slice onion and jalapeno peppers into rings. Set aside. Add a swirl of olive oil to a large nonstick saute pan to coat, and heat over medium to medium-high flame. Spread sweet potato wedges over bottom of pan. When a light golden-brown sear forms (anywhere from 2 to 4 minutes), flip fries with a spatula and repeat on other side, adding a bit more oil if needed. When seared, add about 1/4 cup water to the pan. As water cooks off, quickly test for doneness: fries should be a bit tender, but still firm when poked with a fork. (If not done, add 1/4 cup more water and cook off again). Immediately remove potatoes from pan to a plate. Repeat with remaining fries until all are done. Note: the pan will get hotter as you go, so searing time will decrease. When fries are done, set aside and, in the same pan, quick-saute the sliced onion. To serve, arrange fries on a serving dish, salt to taste, and garnish with sliced onions and jalapenos. Serve warm, with dipping sauce.