Yes, olive oil and vegan butter can be used as substitutes for butter in hollandaise, but they will alter the flavor profile. Olive oil will impart a fruity or peppery note, while vegan butter offers a dairy-free alternative with varying degrees of success depending on the brand.
Hollandaise sauce traditionally relies on the rich, creamy flavor of butter for its characteristic taste and texture. Substituting butter requires understanding how these alternatives will affect the final result.
Olive Oil: Using olive oil, especially extra virgin olive oil, will introduce a distinct flavor. The sauce will be lighter and potentially more bitter, depending on the olive oil's quality. To use olive oil, slowly drizzle it into the egg yolk mixture while whisking constantly, just as you would with melted butter. Be mindful of the olive oil's intensity; a milder olive oil is generally preferred.
Vegan Butter: Vegan butters vary widely in composition and flavor. Some are made from coconut oil, others from vegetable oil blends. Choose a vegan butter that is specifically designed for cooking and has a neutral flavor. Melt the vegan butter and use it in the hollandaise recipe just as you would regular butter. Be aware that some vegan butters may not emulsify as well as dairy butter, potentially leading to a thinner sauce.
Ultimately, the best substitute depends on your desired flavor profile and dietary needs. Experimenting with small batches is recommended to find the right balance.
When using olive oil, consider adding a squeeze of lemon juice at the end to brighten the flavor and balance the oil's richness. This can help mimic the tanginess that butter naturally provides in hollandaise.