Using a large bowl, whisk together all ingredients except for steak tips.
Place steak tips in a large ziptop plastic bag. Add marinade; turn steak tips several times to ensure well coated.
Close bag, squeezing out all air as you close it. Refrigerate for 6-8 hours, or overnight.
Using a large cast iron pan, add vegetable oil and butter. Place over medium-high heat. Once butter has melted, add steak tips. Cook, turning occasionally, until steak reaches desired level of doneness.
Let steak tips rest for 5 minutes before serving.