Make the quick pickling brine: in a small saucepan combine apple cider vinegar, water, sugar, and salt. Heat over medium until sugar and salt dissolve, about 2–3 minutes. Remove from heat.

Place the thinly sliced shallots in a heatproof jar or bowl and pour the warm brine over them, pressing down so they are submerged. Let cool to room temperature, then cover and refrigerate for at least 30 minutes (best 1+ hour).

Pickled shallots will keep in the refrigerator for up to 2 weeks; drain before using.

Avocado relish

Halve and pit the avocado(s). Scoop flesh into a medium bowl and mash with a fork until mostly smooth but still slightly chunky (about 10–15% texture remaining).

Add lime juice, olive oil, finely chopped cilantro, and minced shallot to the mashed avocado. Season with sea salt, freshly ground black pepper, and red pepper flakes if using. Stir gently to combine and taste; adjust salt and lime as needed.

Cover and keep at room temperature if serving immediately, or refrigerate up to 1 hour (bring back to room temperature before assembling for best texture).

Toast & assembly

Prepare hard-boiled eggs: place eggs in a small saucepan and cover with cold water by 1 inch. Bring to a gentle boil over medium-high heat, then reduce heat to maintain a simmer and cook for 9 minutes for firm yolks. Transfer eggs to an ice bath for 5 minutes, then peel and halve or slice.

Toast the sourdough: brush both sides of each slice lightly with olive oil. Toast in a skillet over medium-high heat (2–3 minutes per side) or in a toaster/oven at 200°C/400°F until golden and crisp at the edges (about 5–7 minutes).

Assemble the toast: spread about 1/4 cup of the avocado relish on each slice of toasted sourdough, leaving a small border at the edges.

Top each toast with halved cherry tomatoes (about 1/4 cup per slice), a few thin radish slices, a few pickled shallot slices, and 1/2 of a hard-boiled egg (or sliced egg) per slice as desired.

Finish with microgreens or baby arugula, a light drizzle of olive oil, and a sprinkle of flaky sea salt and a crack of black pepper.

Serve immediately so toast stays crisp. Leftover components (avocado relish, pickled shallots) can be stored separately in the refrigerator.