To start, plug in the Instant Pot and turn it on. Set it to Sauté. Then, add the butter, olive oil, celery, carrots, garlic, onion, and flour. Mix all together, season with a pinch of salt, and sauté for four to five minutes.
If you don't have an instant pot, use a saucepan on a hob.
Image Source: POPSUGAR Photography / Hajar Larbah