Fresh Chili-Lime Sauce
Trim, seed and roughly chop peppers. Place all sauce ingredients except lime juice in a food processor bowl or blender and process for 1-2 min until puréed. Add lime juice and combine well. Sauce can be made up to one day in advance.
Place steak, 1/2 c of sauce and 1 T of oil in a non-reactive dish (glass or stainless steel). Cover and let marinate in the refrigerator for 30-60 min. Preheat oven to 350 degrees. Heat a heavy-bottom skillet over med-high heat. Remove steak from marinade and sear undisturbed for 2 min per side (or grill the steak if preferred). Transfer steak to oven and cook 10-12 min for med doneness. Remove from oven, cover with foil and let rest.
In another skillet or wok, heat remaining 1 T oil over med-high heat. Add ginger and fry 1-2 min until golden and crisp. Transfer to a paper towel. Add onion and fennel to skillet and stir-fry for 2 min. Add snow peas and tomatoes and stir-fry for 1 min.
Thinly slice beef against the grain. Add beef to pan, then Thai basil leaves and 1/2 to 1 c sauce, as desired. Stir to combine, then divide between four serving plates. Garnish with lime and crispy ginger. Serve with jasmine rice and remaining Fresh Chili-Lime Sauce.