Ate de membrillo is a firm, sweet Mexican quince paste made by cooking quince fruit with sugar until thick, then allowing it to set into a sliceable block.It has a concentrated fruity, slightly tart flavor and is often served:In slices with cheese—especially Manchego, panela, or queso frescoAs a dessert or snackIn pastries and other sweets“Ate” refers to Mexican fruit pastes generally; quince (membrillo) is one of the most traditional varieties. It is similar to Spanish dulce de membrillo.
Prepare the quinces: Wash, peel, quarter, and remove the cores. Quince is very firm, so use a sturdy knife. Cut the fruit into 1-inch pieces.
Cook until tender: Place the quince pieces in a saucepan and add enough water to cover them. Bring to a boil, then reduce the heat and simmer for 25–35 minutes, until very soft.
Purée: Drain well, reserving a little cooking liquid. Blend or process the quince until smooth, adding a spoonful of liquid only if necessary.
Add sugar: Return the purée to the saucepan. Stir in the sugar and lemon juice.
Thicken: Cook over low to medium-low heat for 35–50 minutes, stirring frequently with a wooden spoon. The mixture will turn reddish and become very thick. It is ready when it pulls away from the sides of the pan and a spoon dragged across the bottom leaves a clear path.
Set: Lightly oil a small loaf pan or 4 individual ramekins. Spoon in the quince mixture and smooth the top. Let cool, then refrigerate for at least 4 hours, preferably overnight.
Serve: Unmold and cut into slices. Serve with Manchego, queso fresco, panela, or mild cheddar cheese.