Osman Yousefzada has always walked a fine line with his British-Asian heritage, seeking to register it without being pigeonholed for it. His look's always been covered-up, and the dress-slash-long-tunic over pants that recalls the modest South Asian silhouette is a much-repeated signature. (He's been doing the mullet dress we've seen scads of in the past couple weeks for seasons.)

But from the very first look out, his Spring collection felt like something of a new day—a lighter, looser, and sexier day. First there was his measured palette, with just enough Easter-egg yellow and pink, a dash of red, all smoothed out with hits of ivory and olive. That restraint might not mean much at another time, but in this season it merits respect. When it came to embellishment, he relied on the texture of an acid yellow jacquard or an almost weightless French-knot embroidery.

But Yousefzada got most buoyant with his new silhouettes. Those typically rigid lines turned fluid with soft pleats and single- and double-slit skirts. The loose ends of fold-over strapless dresses caught the breeze. Where once he loaded on, here he cut away fabric to expose backs and waists and a skinny sliver of flesh just above the bustline. His pants—all slit to fall open over his minimal sandals—also got a slimmer and longer line. They came with constructed strapless tops or draped blouses. Even when worn under a jersey dress, the look still had a sensual energy.

You have to imagine this new sizzle is one that some of his clientele may balk at. For them, a trio of looks in crisp cotton with halters that wrapped into a bow at the neckline retained the old sense of formality. For the rest, a fun summer is in store.