The selectivity of growth on patterned GaAs (311)A substrates qualitatively differs from that on low-index (100) and (111) substrates. During molecular beam epitaxy (MBE) of (AlGa)As, [01-1] oriented mesa stripes develop a fast-growing convex sidewall. For shallow mesa height, this new growth mechanism produces quasi-planar quantum wires with excellent optical properties. Nanometer-scale self-faceting in atomic hydrogen-assisted MBE transforms these sidewall quantum wires into a linear array of quantum dots with minimized size fluctuations. Upon rotating the mesa stripe from [01-1], a continuous transition occurs from the fast-growing sidewall to the slow-growing sidewall along the perpendicular [-233] direction. This allows their systematic combination at the corner or edge of intersecting mesa stripes appropriately inclined from [01-1], thus offering a novel degree of flexibility for the design of lateral functional semiconductor nanostructures.