Rinse the white rice in a fine mesh strainer under cold water until the water runs mostly clear. This removes excess starch and prevents sticky, clumpy rice.
Set the Instant Pot to saute mode and heat the olive oil and butter. Add the rinsed rice and stir for 1 to 2 minutes, toasting it lightly until a few grains turn opaque.
Pour in the water and add the salt. Stir once to distribute evenly.
Lock the lid, set the valve to sealing, and cook on high pressure for 3 minutes. Once the cook time is done, allow a natural pressure release for 10 minutes, then quick release any remaining pressure.
Open the lid and fluff the rice with a fork. Drizzle the fresh lime juice over the rice and add the lime zest and chopped cilantro. Gently fold everything together until well combined.
Taste and adjust with more lime juice, salt, or cilantro as needed. Serve immediately as a perfect side dish for tacos, burritos, chicken, or any Mexican-inspired meal.