To keep latkes warm, heat oven to 250°F. Have a baking sheet ready. Line a plate with paper towels.

Mix the flour, baking powder, salt and white pepper in a small bowl.

Peel potatoes. With a coarse grating or shredding disc of a food processor or large holes of a grater, grate the potatoes and onion, alternating potato and onion. Transfer mixture to a strainer. Squeeze it by handfuls, removing as much liquid as possible.

Transfer mixture to a bowl. Add egg; mix well. Add flour mixture; mix well.

Heat ½ cup oil in a deep, heavy large skillet over medium heat. For each latke, slide 1 heaping tablespoon of potato mixture into pan. Flatten it with back of a spoon to a pancake about 2½ inches in diameter. Add more pancakes without crowding.

Fry until crisp and golden brown, about 4 minutes per side; use 2 pancake turners to turn them carefully so oil doesn’t splatter. Transfer them to paper towels. Stir batter before frying each batch. Reduce heat if necessary so latkes don’t become too dark. Add more oil to the pan as needed; heat it before adding more latkes. Keep them warm in 1 layer on baking sheet in oven. If last few spoonfuls of batter are watery, leave the liquid in the bowl to prevent splatters.

Before serving, pat latkes with paper towels. Serve hot or warm, with the sauce, extra pepper purée, olives, parsley and hard-boiled egg quarters.

Frozen Peruvian yellow peppers called aji amarillo can be found at markets that carry South American ingredients.

Chef’s Note: To substitute ½ yellow bell pepper for the Peruvian peppers, remove the core and seeds. Broil pepper halves skin side up on foil until skin blackens in spots, about 5 minutes. Enclose pepper in foil. Let cool. Peel with paring knife. Purée with oil, following first paragraph of instructions; add hot pepper sauce to taste.

Makes about 1 cup

Pepper purée: Cut peppers in pieces. In blender, purée peppers with 1 tablespoon oil to a paste. Transfer to a bowl; don’t wash blender yet.

Heat 1 tablespoon oil in a small skillet over medium-low heat. Add onion and cook until softened but not brown, about 3 minutes. Add garlic and heat for a few seconds, stirring. Cool mixture in a bowl.

Transfer onion mixture to blender. Add cheese, ⅓ cup milk and 1 tablespoon plus 1 teaspoon pepper purée. Blend until smooth. If sauce is too thick, gradually blend in more milk at low speed. Scrape down blender sides. Blend sauce again until smooth. Add salt, pepper and more pepper purée to taste. Serve at room temperature.

Reserve remaining pepper purée for serving separately.