I just got back from overseas and while there went to a Michelin star restaurant where we got to sample different fresh olive oils and I can confirm they did taste somewhat like grass.
Well, there are varieties, depending on the olive type you get more or less of a bitter, spicy or fruity taste. Here's a quick guide to Spanish olives used for oils:
- Picual - strong, bitter and spicy, very grassy, also one of the most common single-variety Spanish olive oils. Perfect for cooking meat, or mixing/marinating.
- Arbequina - not as strong, less spicy, with sweet, exotic fruity/grassy flavors. Awesome for making mayonnaise or ali-oli.
- Hojiblanca - somewhat middle-of-the-road, with moderate spice and bitterness, great for salads!
- Cornicabra - strength varies a lot, also spicy if harvested earlier, very sweet if harvested later. Great all-around. Tasty for cooking and for salads.
There are others, but these are the main ones. Early/late harvesting plays a significant role on taste, earlier being more bitter. In general, I love the very greenish-colored cornicabra olive oil, which are full of early harvest chlorophylls, and that are not too spicy.
Unfortunately, most non-Mediterranean (USA, UK...) grocery store extra virgin olive oils may not print the olive variety or is a blend oil produced and marketed for export...
The top recommendation is there, among other reasons, for that taste:
>This oil starts with a slight caramel flavor, but a bitter pungency blooms followed by a pleasant piquancy. We all enjoyed its grassy flavor, which one panelist said gave her “summer vegetable garden vibes.” The oil was rich but not overly fatty. One tester observed, “The way my tongue is responding reminds me of a good matcha—there’s that astringency, and then a long finish.”
100%, that was exactly what it brought to mind for me as well: like I had reached into the lawn mower bag and sprinkled in some essence of grass clippings. No thanks.
If someone wants to call olive oil without grass-clippings-taste "rancid," it's a free country, but that term comes with overbearing negative connotations so I'd personally prefer "aged" or something.