Tips: Use very fresh eggs and keep the water at a gentle simmer for neat poached eggs. The vinegar helps the whites set faster, but avoid boiling hard or the eggs will fray. If the avocado hollandaise thickens or starts to separate, whisk or blend in a little warm water to bring it back together. Leftover sauce can be stored in an airtight container in the refrigerator for up to 2 days; re-warm very gently and thin with warm water as needed. Swap whole wheat or gluten-free English muffins if you like, and substitute baby spinach for arugula if needed. For extra protein, add a slice of smoked salmon on top.