Cut tenderloin into 1/2" thick medallions. Toss with two soy sauces and cornstarch and allow to marinate at least twenty minutes.
After cutting cucumber and first jalapeno, use them to completely line a serving platter, with the cucumber in the center, and the jalapeno as decoration along the edges as shown above.
Heat wok until it is smoking. Add peanut oil and heat until it shimmers. Add onion slices and stir fry until they turn golden. Add ginger, jalapeno and garlic to wok and stir and fry until garlic begins to turn golden.
Add meat in a single layer, and let sit undisturbed for at least one minute, or until the meat is seared well on the bottom. Begin stir frying with the goal of simply searing the outside of the meat, while the inside stays medium rare.