In a small bowl, whisk together the mayonnaise, lime juice, garlic powder, chili powder, paprika, cumin, coriander, cayenne pepper, red pepper flakes and sea salt. Chill until ready to serve.
Using your preferred method, bring a container of water to 120°F. Season the bison ribeye with salt and pepper on both sides, then seal it in a plastic baggie, so no air is contained within the bag.
Submerge the bison ribeye into the water bath. Cook for 1-4 hours. During the last hour, bring the water temperature up to 128°F.
Remove the bison ribeye from the plastic baggie and let rest for ten minutes. While the bison rests, preheat a grill pan over high heat and grease with oil. Sear the bison for 1-2 minutes on each side, just until grill lines appear. Rest five more minutes prior to serving.
Spoon as much aioli as desired across the top of the bison ribeye. Serve along a pile of mashed potatoes and enjoy!