Chill a tall container or the cup of an immersion blender for 5 minutes if possible. Gather a small high-speed blender or an immersion blender and the tall jar it fits; this yields best emulsion.

Add the base: pour 1/2 cup unsweetened soy milk (or aquafaba) into the blender or jar. Add 1 teaspoon Dijon mustard, 1 tablespoon apple cider vinegar, 1/2 teaspoon granulated sugar, 3/4 teaspoon fine sea salt, 1/4 teaspoon garlic powder, and 1/2 teaspoon lemon juice (if using). These ingredients help the emulsion form and season the mayo.

Start blending: with the blender or immersion blender running at medium speed, begin to slowly drizzle in the oil. If using a high-speed blender, pour the oil in a thin, steady stream; if using an immersion blender, keep the head near the bottom so the emulsion forms and then slowly lift as mixture thickens. Total oil to add: 1 cup.

Watch for thickening: after about 3–4 minutes of slow incorporation the mixture should thicken to a mayonnaise consistency. If the mayo is too thick, add up to 1 tablespoon water and blend briefly to reach desired spreadability.

Season with cracked pepper: stop blending and remove lid. Add 2 teaspoons freshly cracked black pepper (adjust to taste). Pulse or stir through with a spoon or briefly blitz twice with the blender to distribute pepper evenly without fully pulverizing the larger flakes — the goal is visible cracked pepper throughout.

Taste and adjust: sample the mayo and add up to an extra 1/4–1/2 teaspoon salt, more lemon juice for brightness, or extra cracked pepper if you like punchier heat. If too thin, chill for 30 minutes to firm up; if separated, blend briefly again starting from the bottom while adding 1–2 teaspoons soy milk.

Transfer and rest: scrape the mayo into a clean jar, seal, and refrigerate for at least 30 minutes to allow flavors to meld. The mayo will thicken slightly as it chills.

Storage: keep refrigerated in a sealed container for up to 7–10 days. Stir before use if any liquid settles on top.