I like the briny umami that the anchovies add to the mayonnaise, but feel free to leave them out if you prefer. (You may wish to add more salt, garlic, or lemon if you do.) The mayonnaise keeps well for up to a week, staying vibrant green and marrying the flavors together nicely. I like the onions best when freshly pickled, but they will also keep in the fridge for a week or more. Wrapping the sandwiches in parchment paper prior to cutting them in half helps them to hold together, but feel free to skip this step in favor of deliciously messy sandwiches.

Green Goddess Mayonnaise (makes enough for 4-6 sandwiches):
1/3 C. packed basil leaves
1/3 C. packed tarragon leaves
1/3 C. packed chopped chives
2 medium-large garlic cloves
2 anchovy fillets
zest and juice of 1/2 a lemon
1/4 teaspoon salt
1/2 C. good mayonnaise (such as Spectrum’s olive oil mayonnaise)

Pickled spring onions (makes enough for 4-6 sandwiches):
2 spring onions, bulb thinly sliced
1/2 C. white wine vinegar
2 teaspoons sugar
1 teaspoon fine sea salt
1/4 teaspoon black peppercorns, lightly crushed

Per sandwich:
2 slices pan bread
1/2 a small, ripe avocado, sliced
2 fat slices fresh mozzarella
1 medium-sized green zebra tomato (or other heirloom tomato), sliced
a few thin slices cucumber
several slices pickled onion
a handful of sprouts (such as broccoli sprouts), rinsed and dried
a couple of small lettuce leaves (butter or romaine), rinsed and dried

Make the mayonnaise: In the bowl of a food processor, combine all ingredients except for the lemon juice (i.e., the basil, tarragon, chives, garlic, anchovies, lemon zest, salt, and mayonnaise) in the bowl of a food processor. Puree smooth, about 2 minutes, scraping down the sides of the bowl as needed. Blend in the lemon juice. Chill until needed. Pickle the onions: In a medium-sized jar, combine the onions slices, vinegar, sugar, salt, and peppercorns. Put the lid on the jar and let sit for at least 10 minutes, shaking a few times to dissolve the salt and sugar. Use immediately or refrigerate until needed, up to 1 week. Assemble the sandwiches: Toast the bread and spread both slices with a thick layer of the mayonnaise. Top with the avocado, mozzarella, tomato, cucumber, pickled onion, sprouts, and lettuce. Sandwich with the other slice of bread and press down gently. Optionally wrap the sandwich in parchment or secure with two toothpicks, and slice in half with a sharp serrated bread knife or chef’s knife.