void setup(){
  size(100,100);
  background(255);
}

void draw(){
  smooth();
  noStroke();
  fill(255,0,0);
  beginShape();
  vertex(50, 15); 
  bezierVertex(50, -5, 90, 5, 50, 40); 
  vertex(50, 15); 
  bezierVertex(50, -5, 10, 5, 50, 40); 
  endShape();
}

Thanks to Luciana.