Heat olive oil in skillet until very hot over medium high heat
Add halibut and sear well on one side for about 5 minutes
Flip when fish no longer sticks to pan
Sear for about 1 minute on other side and then reduce heat slightly and let cook for 5-8 more minutes until cooked through (fish is cooked when internal temp is 145 degrees)
Add drained pineapple, chopped onion and jalapeño and cilantro to a bowl and toss together