In a bowl, dissolve yeast in water. Add 1 1/2 cup of flour, the oil and sugar. Beat for about 3 minutes to make a smooth batter. Gradually stir enough of the remaining flour (about 1 cup) to form a soft dough. Turn out on floured board and knead until smooth and satiny (about 5 minutes), adding flour as needed to prevent sticking.

Place dough in a greased bowl, turn to grease top. Cover and let rise in a warm place until doubled (about 1 hour). Punch dough down, divide into twelve pieces. Shape each into a smooth ball by gently kneading. Then roll each into a smooth rope about 18 inches long, and twist into a pretzel shape. Make a heart shape, and twist rope around itself at the top of the heart and put ends underneath the bottom of the 'heart'.

Place slightly apart on a greased baking sheet. Let rise uncovered until puffy, about 25 minutes. Meanwhile, in a 3 qt. enameled or steel pan (not aluminum) bring soda water mixture to a boil, adjust heat to keep water boiling gently. With a slotted spatula, lower 1 pretzel at a time into pan. Let simmer for 10 seconds on each side, then lift from water, drain briefly, then sprinkle with coarse salt and let stand, uncovered till all have been simmered. Bake in a preheated 425 degrees oven for 12-15 minutes or until golden brown. Transfer to racks, serve warm with butter or mustard. Or let cool completely, wrap airtight, and freeze.

To reheat, place frozen pretzels on ungreased baking sheets and bake in preheated 400 degrees oven for about 10 minutes. Serve with your favorite dipping sauce.