Drain and rinse the cannellini beans well in a colander under cold water. Shake off the extra water.
Warm the olive oil in a 15 cm / 6-inch saucepan over low heat. Add the minced garlic and cook for 1 to 2 minutes, stirring often, until fragrant but not browned. Watch it closely, garlic can turn bitter within seconds if it browns.
Pour the warm garlic oil into a food processor. Add the beans, lemon juice, lemon zest, tahini, cumin, and salt.
Blend for about 1 minute, then stop and scrape down the sides with a rubber spatula.
Blend again for another minute, adding water 1 tablespoon at a time, until the dip is smooth and holds soft peaks on a spoon.
Taste the dip and add more salt or a squeeze of lemon juice if it needs it.
Spread the dip into a shallow bowl. Drizzle with a little more olive oil and scatter the parsley and red pepper flakes over the top.
Serve right away, or chill for later and bring back to room temperature before serving.