Coat beef cubes with flour. Brown beef on all sides in oil in a large Dutch oven. Meanwhile, dissolve bouillon in boiling water; add to Dutch oven. Season with salt and pepper. Simmer, covered, for 1-1/2 hours to 2 hours or until the meat is tender. Add the potatoes, onions, carrots and beans; cook until vegetables are tender, about 30-45 minutes. Mix cornstarch and water; stir into stew and cook until thickened and bubbly. , For biscuits, combine flour, baking powder, salt, oil and milk in a large bowl. Stir to form a light, soft dough, adding more milk if necessary. Drop by tablespoonfuls on top of stew. Brush top of biscuits with melted butter. Bake, uncovered, at 350° for 20-30 minutes or until the biscuits are done.